1
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Tanigaki T, Akashi T, Yoshida T, Harada K, Ishizuka K, Ichimura M, Mitsuishi K, Tomioka Y, Yu X, Shindo D, Tokura Y, Murakami Y, Shinada H. Electron holography observation of individual ferrimagnetic lattice planes. Nature 2024:10.1038/s41586-024-07673-w. [PMID: 38961304 DOI: 10.1038/s41586-024-07673-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 06/04/2024] [Indexed: 07/05/2024]
Abstract
Atomic-scale observations of a specific local area would be considerably beneficial when exploring new fundamental materials and devices. The development of hardware-type aberration correction1,2 in electron microscopy has enabled local structural observations with atomic resolution3-5 as well as chemical and vibration analysis6-8. In magnetic imaging, however, atomic-level spin configurations are analysed by electron energy-loss spectroscopy by placing samples in strong magnetic fields9-11, which destroy the nature of the magnetic ordering in the samples. Although magnetic-field-free observations can visualize the intrinsic magnetic fields of an antiferromagnet by unit-cell averaging12, directly observing the magnetic field of an individual atomic layer of a non-uniform structure is challenging. Here we report that the magnetic fields of an individual lattice plane inside materials with a non-uniform structure can be observed under magnetic-field-free conditions by electron holography with a hardware-type aberration corrector assisted by post-digital aberration correction. The magnetic phases of the net magnetic moments of (111) lattice planes formed by opposite spin orderings between Fe3+ and Mo5+ in a ferrimagnetic double-perovskite oxide (Ba2FeMoO6) were successfully observed. This result opens the door to direct observations of the magnetic lattice in local areas, such as interfaces and grain boundaries, in many materials and devices.
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Affiliation(s)
| | - Tetsuya Akashi
- Research & Development Group, Hitachi, Ltd., Hatoyama, Japan
| | - Takaho Yoshida
- Research & Development Group, Hitachi, Ltd., Hatoyama, Japan
| | - Ken Harada
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
| | | | | | | | - Yasuhide Tomioka
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Xiuzhen Yu
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
| | - Daisuke Shindo
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan
| | - Yoshinori Tokura
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
- Department of Applied Physics and Tokyo College, The University of Tokyo, Tokyo, Japan
| | - Yasukazu Murakami
- Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University, Fukuoka, Japan
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2
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Ning Z, Qian J, Liu Y, Chen F, Zhang M, Deng L, Yuan X, Ge Q, Jin H, Zhang G, Peng W, Qiao S, Mu G, Chen Y, Li W. Coexistence of Ferromagnetism and Superconductivity at KTaO 3 Heterointerfaces. NANO LETTERS 2024; 24:7134-7141. [PMID: 38828962 DOI: 10.1021/acs.nanolett.4c02500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2024]
Abstract
The coexistence of superconductivity and ferromagnetism is a long-standing issue in superconductivity due to the antagonistic nature of these two ordered states. Experimentally identifying and characterizing novel heterointerface superconductors that coexist with magnetism presents significant challenges. Here, we report the observation of two-dimensional long-range ferromagnetic order in a KTaO3 heterointerface superconductor, showing the coexistence of superconductivity and ferromagnetism. Remarkably, our direct current superconducting quantum interference device measurements reveal an in-plane magnetization hysteresis loop persisting above room temperature. Moreover, first-principles calculations and X-ray magnetic circular dichroism measurements provide decisive insights into the origin of the observed robust ferromagnetism, attributing it to oxygen vacancies that localize electrons in nearby Ta 5d states. Our findings suggest KTaO3 heterointerfaces as time-reversal symmetry breaking superconductors, injecting fresh momentum into the exploration of the intricate interplay between superconductivity and magnetism enhanced by the strong spin-orbit coupling inherent to the heavy Ta in 5d orbitals.
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Affiliation(s)
- Zhongfeng Ning
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Jiahui Qian
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Yixin Liu
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fan Chen
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Mingzhu Zhang
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Liwei Deng
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xinli Yuan
- Thermo Fisher Scientific China, Shanghai 201203, China
| | - Qingqin Ge
- Thermo Fisher Scientific China, Shanghai 201203, China
| | - Hua Jin
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Guanqun Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Wei Peng
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shan Qiao
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Gang Mu
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yan Chen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Wei Li
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
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3
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Düring PM, Rosenberger P, Baumgarten L, Alarab F, Lechermann F, Strocov VN, Müller M. Tunable 2D Electron- and 2D Hole States Observed at Fe/SrTiO 3 Interfaces. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2309217. [PMID: 38245856 DOI: 10.1002/adma.202309217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 10/27/2023] [Indexed: 01/22/2024]
Abstract
Oxide electronics provide the key concepts and materials for enhancing silicon-based semiconductor technologies with novel functionalities. However, a basic but key property of semiconductor devices still needs to be unveiled in its oxidic counterparts: the ability to set or even switch between two types of carriers-either negatively (n) charged electrons or positively (p) charged holes. Here, direct evidence for individually emerging n- or p-type 2D band dispersions in STO-based heterostructures is provided using resonant photoelectron spectroscopy. The key to tuning the carrier character is the oxidation state of an adjacent Fe-based interface layer: For Fe and FeO, hole bands emerge in the empty bandgap region of STO due to hybridization of Ti- and Fe- derived states across the interface, while for Fe3O4 overlayers, an 2D electron system is formed. Unexpected oxygen vacancy characteristics arise for the hole-type interfaces, which as of yet had been exclusively assigned to the emergence of 2DESs. In general, this finding opens up the possibility to straightforwardly switch the type of conductivity at STO interfaces by the oxidation state of a redox overlayer. This will extend the spectrum of phenomena in oxide electronics, including the realization of combined n/p-type all-oxide transistors or logic gates.
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Affiliation(s)
- Pia M Düring
- Fachbereich Physik, Universität Konstanz, 78457, Konstanz, Germany
| | - Paul Rosenberger
- Fachbereich Physik, Universität Konstanz, 78457, Konstanz, Germany
- Fakultät Physik, Technische Universität Dortmund, 44221, Dortmund, Germany
| | - Lutz Baumgarten
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-6), 52425, Jülich, Germany
| | - Fatima Alarab
- Paul Scherrer Institute, Swiss Light Source, Villingen PSI, CH-5232, Switzerland
| | - Frank Lechermann
- Institut für Theoretische Physik III, Ruhr-Universität Bochum, 44780, Bochum, Germany
| | - Vladimir N Strocov
- Paul Scherrer Institute, Swiss Light Source, Villingen PSI, CH-5232, Switzerland
| | - Martina Müller
- Fachbereich Physik, Universität Konstanz, 78457, Konstanz, Germany
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4
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Yang W, Ni Y, Liu Y, Feng X, Hu J, Liu WM, Wu R, Fu Z. Origin of Interfacial Orbital Reconstruction in Perovskite Superlattices. PHYSICAL REVIEW LETTERS 2024; 132:126201. [PMID: 38579216 DOI: 10.1103/physrevlett.132.126201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 02/01/2024] [Accepted: 02/27/2024] [Indexed: 04/07/2024]
Abstract
The competition between on-site electronic correlation and local crystal field stands out as a captivating topic in research. However, its physical ramifications often get overshadowed by influences of strong periodic potential and orbital hybridization. The present study reveals this competition may become more pronounced or even dominant in two-dimensional systems, driven by the combined effects of dimensional confinement and orbital anisotropy. This leads to electronic orbital reconstruction in certain perovskite superlattices or thin films. To explore the emerging physics, we investigate the interfacial orbital disorder-order transition with an effective Hamiltonian and how to modulate this transition through strains.
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Affiliation(s)
- Wenbo Yang
- College of Physics and Electronic Information, Yunnan Normal University, Kunming 650500, China
- Yunnan Key Laboratory of Opto-Electronic Information Technology, Kunming 650500, China
| | - Yu Ni
- College of Physics and Electronic Information, Yunnan Normal University, Kunming 650500, China
- Yunnan Key Laboratory of Opto-Electronic Information Technology, Kunming 650500, China
| | - Yingkai Liu
- College of Physics and Electronic Information, Yunnan Normal University, Kunming 650500, China
- Yunnan Key Laboratory of Opto-Electronic Information Technology, Kunming 650500, China
| | - Xiaobo Feng
- College of Physics and Electronic Information, Yunnan Normal University, Kunming 650500, China
- Yunnan Key Laboratory of Opto-Electronic Information Technology, Kunming 650500, China
| | - Jiangping Hu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Wu-Ming Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Ruqian Wu
- Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA
| | - Zhaoming Fu
- College of Physics and Electronic Information, Yunnan Normal University, Kunming 650500, China
- Yunnan Key Laboratory of Opto-Electronic Information Technology, Kunming 650500, China
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5
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Li T, Deng S, Qi H, Zhu T, Chen Y, Wang H, Zhu F, Liu H, Wang J, Guo EJ, Diéguez O, Chen J. High-Temperature Ferroic Glassy States in SrTiO_{3}-Based Thin Films. PHYSICAL REVIEW LETTERS 2023; 131:246801. [PMID: 38181148 DOI: 10.1103/physrevlett.131.246801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 08/19/2023] [Accepted: 10/24/2023] [Indexed: 01/07/2024]
Abstract
Disordered ferroics hold great promise for next-generation magnetoelectric devices because their lack of symmetry constraints implies negligible hysteresis with low energy costs. However, the transition temperature and the magnitude of polarization and magnetization are still too low to meet application requirements. Here, taking the prototype perovskite of SrTiO_{3} as an instance, we realize a coexisting spin and dipole reentrant glass states in SrTiO_{3} homoepitaxial films via manipulation of local symmetry. Room-temperature saturation magnetization and spontaneous polarization reach ∼ 10 emu/cm^{3} and ∼ 25 μC/cm^{2}, respectively, with high transition temperatures (101 K and 236 K for spin and dipole glass temperatures and 556 K and 1100 K for Curie temperatures, respectively). Our atomic-scale investigation points out an underlying mechanism, where the Ti/O-defective unit cells break the local translational and orbital symmetry to drive the formation of unusual slush states. This study advances our understanding of the nature of the intricate couplings of ferroic glasses. Our approach could be applied to numerous perovskite oxides for the simultaneous control of the local magnetic and polar orderings and for the exploration of the underlying physics.
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Affiliation(s)
- Tianyu Li
- Beijing Advanced Innovation Center for Materials Genome Engineering, University of Science and Technology Beijing, Beijing 100083, China
- Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China
| | - Shiqing Deng
- Beijing Advanced Innovation Center for Materials Genome Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - He Qi
- Beijing Advanced Innovation Center for Materials Genome Engineering, University of Science and Technology Beijing, Beijing 100083, China
- Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China
| | - Tao Zhu
- Spallation Neutron Source Science Center, Dongguan 523803, China
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Yu Chen
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Huanhua Wang
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Fangyuan Zhu
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China
| | - Hui Liu
- Beijing Advanced Innovation Center for Materials Genome Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Jiaou Wang
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Er-Jia Guo
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Oswaldo Diéguez
- Department of Materials Science and Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Jun Chen
- Beijing Advanced Innovation Center for Materials Genome Engineering, University of Science and Technology Beijing, Beijing 100083, China
- Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China
- Hainan University, Haikou 570228, China
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6
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Gan Y, Yang F, Kong L, Chen X, Xu H, Zhao J, Li G, Zhao Y, Yan L, Zhong Z, Chen Y, Ding H. Light-Induced Giant Rashba Spin-Orbit Coupling at Superconducting KTaO 3 (110) Heterointerfaces. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023:e2300582. [PMID: 36972144 DOI: 10.1002/adma.202300582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 03/07/2023] [Indexed: 05/16/2023]
Abstract
The 2D electron system (2DES) at the KTaO3 surface or heterointerface with 5d orbitals hosts extraordinary physical properties, including a stronger Rashba spin-orbit coupling (RSOC), higher superconducting transition temperature, and potential of topological superconductivity. Herein, a huge enhancement of RSOC under light illumination achieved at a superconducting amorphous-Hf0.5 Zr0.5 O2 /KTaO3 (110) heterointerfaces is reported. The superconducting transition is observed with Tc = 0.62 K and the temperature-dependent upper critical field reveals the interaction between spin-orbit scattering and superconductivity. A strong RSOC with Bso = 1.9 T is revealed by weak antilocalization in the normal state, which undergoes sevenfold enhancement under light illumination. Furthermore, RSOC strength develops a dome-shaped dependence of carrier density with the maximum of Bso = 12.6 T achieved near the Lifshitz transition point nc ≈ 4.1 × 1013 cm-2 . The highly tunable giant RSOC at KTaO3 (110)-based superconducting interfaces show great potential for spintronics.
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Affiliation(s)
- Yulin Gan
- Beijing National Laboratory of Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Fazhi Yang
- Beijing National Laboratory of Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Lingyuan Kong
- Beijing National Laboratory of Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Xuejiao Chen
- Key Laboratory of Magnetic Materials and Devices and Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering (NIMTE), Chinese Academy of Sciences, Ningbo, 315201, China
| | - Hao Xu
- Beijing National Laboratory of Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Jin Zhao
- Beijing National Laboratory of Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Gang Li
- Beijing National Laboratory of Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Yuchen Zhao
- Beijing National Laboratory of Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Lei Yan
- Beijing National Laboratory of Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Zhicheng Zhong
- Key Laboratory of Magnetic Materials and Devices and Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering (NIMTE), Chinese Academy of Sciences, Ningbo, 315201, China
| | - Yunzhong Chen
- Beijing National Laboratory of Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Hong Ding
- Beijing National Laboratory of Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Tsung-Dao Lee Institute & School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, 200240, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing, 100190, China
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7
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Shirsath SE, Assadi MHN, Zhang J, Kumar N, Gaikwad AS, Yang J, Maynard-Casely HE, Tay YY, Du J, Wang H, Yao Y, Chen Z, Zhang J, Zhang S, Li S, Wang D. Interface-Driven Multiferroicity in Cubic BaTiO 3-SrTiO 3 Nanocomposites. ACS NANO 2022; 16:15413-15424. [PMID: 36070478 DOI: 10.1021/acsnano.2c07215] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Perovskite multiferroics have drawn significant attention in the development of next-generation multifunctional electronic devices. However, the majority of existing multiferroics exhibit ferroelectric and ferromagnetic orderings only at low temperatures. Although interface engineering in complex oxide thin films has triggered many exotic room-temperature functionalities, the desired coupling of charge, spin, orbital and lattice degrees of freedom often imposes stringent requirements on deposition conditions, layer thickness and crystal orientation, greatly hindering their cost-effective large-scale applications. Herein, we report an interface-driven multiferroicity in low-cost and environmentally friendly bulk polycrystalline material, namely cubic BaTiO3-SrTiO3 nanocomposites which were fabricated through a simple, high-throughput solid-state reaction route. Interface reconstruction in the nanocomposites can be readily controlled by the processing conditions. Coexistence of room-temperature ferromagnetism and ferroelectricity, accompanying a robust magnetoelectric coupling in the nanocomposites, was confirmed both experimentally and theoretically. Our study explores the 'hidden treasure at the interface' by creating a playground in bulk perovskite oxides, enabling a broad range of applications that are challenging with thin films, such as low-power-consumption large-volume memory and magneto-optic spatial light modulator.
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Affiliation(s)
- Sagar E Shirsath
- School of Materials Science and Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - M Hussein N Assadi
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Ji Zhang
- School of Materials Science and Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Nitish Kumar
- School of Materials Science and Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Anil S Gaikwad
- Department of Physics, Vivekanand College, Aurangabad 431001, Maharashtra, India
| | - Jack Yang
- School of Materials Science and Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia
- UNSW Materials and Manufacturing Futures Institute, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Helen E Maynard-Casely
- Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, New South Wales 2234, Australia
| | - Yee Yan Tay
- Facility for Analysis, Characterization, Testing and Simulation and School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
| | - Jianhao Du
- School of Materials Science and Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Haoyu Wang
- School of Materials Science and Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Yin Yao
- Mark Wainwright Analytical Centre UNSW Sydney, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Zibin Chen
- Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University, Hong Kong, China
| | - Jinxing Zhang
- Department of Physics, Beijing Normal University, 100875 Beijing, China
| | - Shujun Zhang
- Institute for Superconducting and Electronic Materials, Australian Institute of Innovative Materials, University of Wollongong, Wollongong, New South Wales 2500, Australia
| | - Sean Li
- School of Materials Science and Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia
- UNSW Materials and Manufacturing Futures Institute, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Danyang Wang
- School of Materials Science and Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia
- UNSW Materials and Manufacturing Futures Institute, The University of New South Wales, Sydney, New South Wales 2052, Australia
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8
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Shiraishi A, Kimura S, He X, Watanabe N, Katase T, Ide K, Minohara M, Matsuzaki K, Hiramatsu H, Kumigashira H, Hosono H, Kamiya T. Design, Synthesis, and Optoelectronic Properties of the High-Purity Phase in Layered AETMN 2 ( AE = Sr, Ba; TM = Ti, Zr, Hf) Semiconductors. Inorg Chem 2022; 61:6650-6659. [PMID: 35442660 DOI: 10.1021/acs.inorgchem.2c00604] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report the synthesis and optoelectronic properties of high phase-purity (>94 mol %) bulk polycrystals of KCoO2-type layered nitrides AETMN2 (AE = Sr, Ba; and TM = Ti, Zr, Hf), which are expected to exhibit unique electron transport properties originating from their natural two-dimensional (2D) electronic structure, but high-purity intrinsic samples have yet been reported. The bulks were synthesized using a solid-state reaction between AENH and TMN precursors with NaN3 to achieve high N chemical potential during the reaction. The AETMN2 bulks are n-type semiconductors with optical band gaps of 1.63 eV for SrTiN2, 1.97 eV for BaZrN2, and 2.17 eV for BaHfN2. SrTiN2 and BaZrN2 bulks show degenerated electron conduction due to the natural high-density electron doping and paramagnetic behavior in all of the temperature ranges examined, while such unintentional carrier generation is largely suppressed in BaHfN2, which exhibits nondegenerated electron conduction. The BaHfN2 sample also exhibits weak ferromagnetic behavior at temperatures lower than 35 K. Density functional theory calculations suggest that the high-density electron carriers in SrTiN2 come from oxygen impurity substitution at the N site (ON) acting as a shallow donor even if the high-N chemical potential synthesis conditions are employed. On the other hand, the formation energy of ON becomes larger in BaHfN2 because of the stronger TM-N chemical bonds. Present results demonstrate that the easiness of impurity incorporation is designed by density functional calculations to produce a more intrinsic semiconductor in wider chemical conditions, opening a way to cultivating novel functional materials that are sensitive to atmospheric impurities and defects.
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Affiliation(s)
- Akihiro Shiraishi
- Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Shigeru Kimura
- Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Xinyi He
- Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Naoto Watanabe
- Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Takayoshi Katase
- Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Keisuke Ide
- Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Makoto Minohara
- Research Institute for Advanced Electronics and Photonics, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan
| | - Kosuke Matsuzaki
- Materials Research Center for Element Strategy, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Hidenori Hiramatsu
- Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan.,Materials Research Center for Element Strategy, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Hiroshi Kumigashira
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Hideo Hosono
- Materials Research Center for Element Strategy, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Toshio Kamiya
- Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan.,Materials Research Center for Element Strategy, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
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9
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Liu MJ, Guo J, Hoffman AS, Stenlid JH, Tang MT, Corson ER, Stone KH, Abild-Pedersen F, Bare SR, Tarpeh WA. Catalytic Performance and Near-Surface X-ray Characterization of Titanium Hydride Electrodes for the Electrochemical Nitrate Reduction Reaction. J Am Chem Soc 2022; 144:5739-5744. [PMID: 35315649 DOI: 10.1021/jacs.2c01274] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The electrochemical nitrate reduction reaction (NO3RR) on titanium introduces significant surface reconstruction and forms titanium hydride (TiHx, 0 < x ≤ 2). With ex situ grazing-incidence X-ray diffraction (GIXRD) and X-ray absorption spectroscopy (XAS), we demonstrated near-surface TiH2 enrichment with increasing NO3RR applied potential and duration. This quantitative relationship facilitated electrochemical treatment of Ti to form TiH2/Ti electrodes for use in NO3RR, thereby decoupling hydride formation from NO3RR performance. A wide range of NO3RR activity and selectivity on TiH2/Ti electrodes between -0.4 and -1.0 VRHE was observed and analyzed with density functional theory (DFT) calculations on TiH2(111). This work underscores the importance of relating NO3RR performance with near-surface electrode structure to advance catalyst design and operation.
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Affiliation(s)
- Matthew J Liu
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
| | - Jinyu Guo
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
| | - Adam S Hoffman
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Joakim Halldin Stenlid
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States.,SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Michael T Tang
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States.,SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Elizabeth R Corson
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
| | - Kevin H Stone
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Frank Abild-Pedersen
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Simon R Bare
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.,SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - William A Tarpeh
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States.,SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
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10
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Dawn R, Zzaman M, Faizal F, Kiran C, Kumari A, Shahid R, Panatarani C, Joni IM, Verma VK, Sahoo SK, Amemiya K, Singh VR. Origin of Magnetization in Silica-coated Fe 3O 4 Nanoparticles Revealed by Soft X-ray Magnetic Circular Dichroism. BRAZILIAN JOURNAL OF PHYSICS 2022; 52:99. [PMCID: PMC9014780 DOI: 10.1007/s13538-022-01102-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 03/31/2022] [Indexed: 05/24/2023]
Abstract
Abstract
Magnetite (Fe3O4) nanoparticles (NPs) and SiO2-coated Fe3O4 nanoparticles have successfully been synthesized using co-precipitation and modified Stöber methods, respectively. The samples were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, high-resolution transmission electron microscopy (HRTEM), vibrating sample magnetometer (VSM) techniques, X-ray absorption spectroscopy (XAS), and X-ray magnetic circular dichroism (XMCD). XRD and FTIR data confirmed the structural configuration of a single-phase Fe3O4 and the successful formation of SiO2-coated Fe3O4 NPs. XRD also confirmed that we have succeeded to synthesize nano-meter size of Fe3O4 NPs. HRTEM images showed the increasing thickness of SiO2-coated Fe3O4 with the addition of the Tetraethyl Orthosilicate (TEOS). Room temperature VSM analysis showed the magnetic behaviour of Fe3O4 and its variations that occurred after SiO2 coating. The magnetic behaviour is further authenticated by XAS spectra analysis which cleared about the existence of SiO2 shells that have transformed the crystal as well as the local structures of the magnetite NPs. We have performed XMCD measurements, which is a powerful element-specific technique to find out the origin of magnetization in SiO2-coated Fe3O4 NPs, that verified a decrease in magnetization with increasing thickness of the SiO2 coating. Graphical Abstract Magnetite (Fe3O4) nanoparticles (NPs) and SiO2-coated Fe3O4 nanoparticles have successfully been synthesized using co-precipitation and modified Stöber methods, respectively. The samples were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, high-resolution transmission electron microscopy (HRTEM), vibrating sample magnetometer (VSM) techniques, X-ray absorption spectroscopy (XAS), and X-ray magnetic circular dichroism (XMCD). XRD and FTIR data confirmed the structural configuration of a single-phase Fe3O4 and the successful formation of SiO2-coated Fe3O4 NPs. XRD also confirmed that we have succeeded to synthesize nano-meter size of Fe3O4 NPs. HRTEM images showed the increasing thickness of SiO2-coated Fe3O4 with the addition of the Tetraethyl Orthosilicate (TEOS). Room temperature VSM analysis showed the magnetic behaviour of Fe3O4 and its variations that occurred after SiO2 coating. The magnetic behaviour is further authenticated by XAS spectra analysis which cleared about the existence of SiO2 shells that have transformed the crystal as well as the local structures of the magnetite NPs. We have performed XMCD measurements, which is a powerful element-specific technique to find out the origin of magnetization in SiO2-coated Fe3O4 NPs, that verified a decrease in magnetization with increasing thickness of the SiO2 coating. ![]()
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Affiliation(s)
- R. Dawn
- Department of Physics, Central University of South Bihar, Gaya-824236, India
| | - M. Zzaman
- Department of Physics, Central University of South Bihar, Gaya-824236, India
- Department of Physics, Jamia Millia Islamia (Central University), New Delhi, 110025 India
| | - F. Faizal
- Department of Physics, Universitas Padjadjaran, Jl. Raya Bandung-Sumedang Km 21, West Java, Bandung, 45363 Indonesia
- Functional Nano Powder University Centre of Excellence (FiNder U CoE), Universitas Padjadjaran, Jl. Raya Bandung-Sumedang, Km 21, West Java, Bandung, 45363 Indonesia
| | - C. Kiran
- Department of Animal Sciences, Central University of Kashmir, Ganderbal, 191201 India
| | - A. Kumari
- Department of Physics, Central University of South Bihar, Gaya-824236, India
| | - R. Shahid
- Department of Physics, Jamia Millia Islamia (Central University), New Delhi, 110025 India
| | - C. Panatarani
- Department of Physics, Universitas Padjadjaran, Jl. Raya Bandung-Sumedang Km 21, West Java, Bandung, 45363 Indonesia
- Functional Nano Powder University Centre of Excellence (FiNder U CoE), Universitas Padjadjaran, Jl. Raya Bandung-Sumedang, Km 21, West Java, Bandung, 45363 Indonesia
| | - I. M. Joni
- Department of Physics, Universitas Padjadjaran, Jl. Raya Bandung-Sumedang Km 21, West Java, Bandung, 45363 Indonesia
- Functional Nano Powder University Centre of Excellence (FiNder U CoE), Universitas Padjadjaran, Jl. Raya Bandung-Sumedang, Km 21, West Java, Bandung, 45363 Indonesia
| | - V. K. Verma
- Department of Physics, Madanapalle Institute of Technology & Science, Madanapalle, 517325 India
| | - S. K. Sahoo
- Department of Metallurgical and Materials Engineering, National Institute of Technology, Rourkela, 769008 India
| | - K. Amemiya
- Photon Factory, IMSS, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801 Japan
| | - V. R. Singh
- Department of Physics, Central University of South Bihar, Gaya-824236, India
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11
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In-plane quasi-single-domain BaTiO 3 via interfacial symmetry engineering. Nat Commun 2021; 12:6784. [PMID: 34811372 PMCID: PMC8608839 DOI: 10.1038/s41467-021-26660-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 10/19/2021] [Indexed: 11/08/2022] Open
Abstract
The control of the in-plane domain evolution in ferroelectric thin films is not only critical to understanding ferroelectric phenomena but also to enabling functional device fabrication. However, in-plane polarized ferroelectric thin films typically exhibit complicated multi-domain states, not desirable for optoelectronic device performance. Here we report a strategy combining interfacial symmetry engineering and anisotropic strain to design single-domain, in-plane polarized ferroelectric BaTiO3 thin films. Theoretical calculations predict the key role of the BaTiO3/PrScO3 [Formula: see text] substrate interfacial environment, where anisotropic strain, monoclinic distortions, and interfacial electrostatic potential stabilize a single-variant spontaneous polarization. A combination of scanning transmission electron microscopy, piezoresponse force microscopy, ferroelectric hysteresis loop measurements, and second harmonic generation measurements directly reveals the stabilization of the in-plane quasi-single-domain polarization state. This work offers design principles for engineering in-plane domains of ferroelectric oxide thin films, which is a prerequisite for high performance optoelectronic devices.
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12
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Leermakers I, Rubi K, Yang M, Kerdi B, Goiran M, Escoffier W, Rana AS, Smink AEM, Brinkman A, Hilgenkamp H, Maan JC, Zeitler U. Quantum oscillations in an optically-illuminated two-dimensional electron system at the LaAlO 3/SrTiO 3interface. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:465002. [PMID: 34433152 DOI: 10.1088/1361-648x/ac211a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 08/25/2021] [Indexed: 06/13/2023]
Abstract
We have investigated the illumination effect on the magnetotransport properties of a two-dimensional electron system at the LaAlO3/SrTiO3interface. The illumination significantly reduces the zero-field sheet resistance, eliminates the Kondo effect at low-temperature, and switches the negative magnetoresistance into the positive one. A large increase in the density of high-mobility carriers after illumination leads to quantum oscillations in the magnetoresistance originating from the Landau quantization. The carrier density (∼2 × 1012 cm-2) and effective mass (∼1.7me) estimated from the oscillations suggest that the high-mobility electrons occupy thedxz/yzsubbands of Ti:t2gorbital extending deep within the conducting sheet of SrTiO3. Our results demonstrate that the illumination which induces additional carriers at the interface can pave the way to control the Kondo-like scattering and study the quantum transport in the complex oxide heterostructures.
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Affiliation(s)
- I Leermakers
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands
| | - K Rubi
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands
| | - M Yang
- Laboratoire National des Champs Magnétiques Intenses (LNCMI-EMFL), Université de Toulouse, CNRS, INSA, UPS, 143 Avenue de Rangueil, 31400 Toulouse, France
| | - B Kerdi
- Laboratoire National des Champs Magnétiques Intenses (LNCMI-EMFL), Université de Toulouse, CNRS, INSA, UPS, 143 Avenue de Rangueil, 31400 Toulouse, France
| | - M Goiran
- Laboratoire National des Champs Magnétiques Intenses (LNCMI-EMFL), Université de Toulouse, CNRS, INSA, UPS, 143 Avenue de Rangueil, 31400 Toulouse, France
| | - W Escoffier
- Laboratoire National des Champs Magnétiques Intenses (LNCMI-EMFL), Université de Toulouse, CNRS, INSA, UPS, 143 Avenue de Rangueil, 31400 Toulouse, France
| | - A S Rana
- MESA + Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
| | - A E M Smink
- MESA + Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
| | - A Brinkman
- MESA + Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
| | - H Hilgenkamp
- MESA + Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
| | - J C Maan
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands
| | - U Zeitler
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands
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13
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Sun Y, Yang J, Li S, Wang D. Defect engineering in perovskite oxide thin films. Chem Commun (Camb) 2021; 57:8402-8420. [PMID: 34351323 DOI: 10.1039/d1cc02276h] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Perovskite oxide thin films are a category of multifunctional materials that have intriguing electrical, magnetic, and photovoltaic properties that can be harnessed combinatorially in future microelectronic devices. However, the inevitable existence of defects in perovskites, regardless of the materials' processing conditions, plays a significant role in their functional properties, which could be either detrimental or beneficial, depending on the exact chemical nature of these defects. As such, defect engineering is an important research area in perovskite thin films that aims at understanding the chemical nature of the defects, from which the physical properties of materials can be more precisely manipulated. Here, we review the common defects in perovskite oxide thin films, which include point defects, dopants, domains and domain walls. The factors that impact the appearance and existence of defects and the corresponding mechanisms are also discussed. While summarizing our previous work, the state-of-the-art in the field from other groups has also been discussed. Most of the defects exist as defect dipoles that affect the oxidation states of relevant ions and induce anomalous behaviors, such as ferroelectricity in otherwise non-ferroelectric thin films, as well as enhanced electrical conductivity in insulators. Furthermore, the couplings between defect dipoles and other degrees of freedom including epitaxial strains and interfaces also provide new strategies to modulate the functional properties of perovskite thin films. Particularly, the coupling between defects and domain wall motion can be regarded as a universal tool to modulate the electric and magnetic properties of thin films of perovskite oxides. It is our hope that this review could promote defect engineering as a general regulation strategy to embellish the functional properties of perovskite oxide thin films.
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Affiliation(s)
- Yunlong Sun
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Sydney, NSW 2052, Australia.
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14
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He X, Katase T, Ide K, Hosono H, Kamiya T. Ion Substitution Effect on Defect Formation in Two-Dimensional Transition Metal Nitride Semiconductors, AETiN 2 ( AE = Ca, Sr, and Ba). Inorg Chem 2021; 60:10227-10234. [PMID: 34237216 DOI: 10.1021/acs.inorgchem.1c00526] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A layered semiconductor, SrTiN2, has an interesting crystal structure as a two-dimensional (2D) electron system embedded in a three-dimensional bulk periodic structure because it has alternate stacking of a SrN blocking layer and a TiN conduction layer, in which the Ti 3dxy orbital forms the conduction band minimum (CBM) similar to the SrTiO3-based thin-film heterostructure. However, SrTiN2 has been reported to exhibit nearly degenerate conduction, but we reported that it would be due to the easy formation of nitrogen vacancies and oxygen impurities from air. In this paper, we extend the materials to family compounds, alkaline earth (AE) ion-substituted, AETiN2 (AE = Ca, Sr, and Ba), and investigated how we can suppress the defect formation by (hybrid) density functional theory calculations. All AETiN2 compounds possess thermodynamic stability in the wide nitrogen (N) chemical potential window. Especially, CaTiN2 is the most stable even against N-poor conditions. Unintentional carrier generation occurs due to the nitrogen vacancies (VN), oxygen substitution (ON), and hydrogen anion substitution (HN) at the nitrogen sites. The VN and HN impurities can be suppressed under N-moderate and N-rich conditions. The ON defect is easily formed in SrTiN2 and also in BaTiN2 under N-rich conditions, but its formation can be suppressed in CaTiN2. Present results suggest that high-purity CaTiN2 can be obtained under wider N chemical conditions, which would lead to the realization of the novel functional properties originating from Ti 3dxy 2D bands embedded in the bulk crystal structure.
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Affiliation(s)
- Xinyi He
- Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Takayoshi Katase
- Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Keisuke Ide
- Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Hideo Hosono
- Materials Research Center for Element Strategy, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Toshio Kamiya
- Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan.,Materials Research Center for Element Strategy, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
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15
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Wei Y, Weng Z, Guo L, An L, Yin J, Sun S, Da P, Wang R, Xi P, Yan CH. Activation Strategies of Perovskite-Type Structure for Applications in Oxygen-Related Electrocatalysts. SMALL METHODS 2021; 5:e2100012. [PMID: 34927915 DOI: 10.1002/smtd.202100012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 03/01/2021] [Indexed: 06/14/2023]
Abstract
The oxygen-related electrochemical process, including the oxygen evolution reaction and oxygen reduction reaction, is usually a kinetically sluggish reaction and thus dominates the whole efficiency of energy storage and conversion devices. Owing to the dominant role of the oxygen-related electrochemical process in the development of electrochemical energy, an abundance of oxygen-related electrocatalysts is discovered. Among them, perovskite-type materials with flexible crystal and electronic structures have been researched for a long time. However, most perovskite materials still show low intrinsic activity, which highlights the importance of activation strategies for perovskite-type structures to improve their intrinsic activity. In this review, the recent progress of the activation strategies for perovskite-type structures is summarized and their related applications in oxygen-related electrocatalysis reactions, including electrochemistry water splitting, metal-air batteries, and solid oxide fuel cells are discussed. Furthermore, the existing challenges and the future perspectives for the designing of ideal perovskite-type structure catalysts are proposed and discussed.
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Affiliation(s)
- Yicheng Wei
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China
| | - Zheng Weng
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China
| | - Linchuan Guo
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China
| | - Li An
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China
| | - Jie Yin
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China
| | - Shuoyi Sun
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China
| | - Pengfei Da
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China
| | - Rui Wang
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China
| | - Pinxian Xi
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China
| | - Chun-Hua Yan
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, PKU-HKU Joint Laboratory in Rare Earth Materials and Bioinorganic Chemistry, College of Chemistry and Molecular Engineering Peking University, Beijing, 100871, China
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16
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Chen J, Zhang Z, Luo L, Lu Y, Song C, Cheng D, Chen X, Li W, Ren Z, Wang J, Tian H, Zhang Z, Han G. Reversible magnetism transition at ferroelectric oxide heterointerface. Sci Bull (Beijing) 2020; 65:2094-2099. [PMID: 36732962 DOI: 10.1016/j.scib.2020.09.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 08/11/2020] [Accepted: 09/01/2020] [Indexed: 02/04/2023]
Abstract
Oxide heterointerface is a platform to create unprecedented two-dimensional electron gas, superconductivity and ferromagnetism, arising from a polar discontinuity at the interface. In particular, the ability to tune these intriguing effects paves a way to elucidate their fundamental physics and to develop novel electronic/magnetic devices. In this work, we report for the first time that a ferroelectric polarization screening at SrTiO3/PbTiO3 interface is able to drive an electronic construction of Ti atom, giving rise to room-temperature ferromagnetism. Surprisingly, such ferromagnetism can be switched to antiferromagnetism by applying a magnetic field, which is reversible. A coupling of itinerant electrons with local moments at interfacial Ti 3d orbital was proposed to explain the magnetism. The localization of the itinerant electrons under a magnetic field is responsible for the suppression of magnetism. These findings provide new insights into interfacial magnetism and their control by magnetic field relevant interfacial electrons promising for device applications.
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Affiliation(s)
- Jialu Chen
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Cyrus Tang Center for Sensor Materials and Application, Zhejiang University, Hangzhou 310027, China
| | - Zijun Zhang
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Cyrus Tang Center for Sensor Materials and Application, Zhejiang University, Hangzhou 310027, China; Center of Electron Microscope, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Liang Luo
- Department of Physics and Astronomy, Iowa State University and Ames Laboratory-USDOE, Ames, IA 50011, USA
| | - Yunhao Lu
- Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Cheng Song
- Key Laboratory of Advanced Materials (Ministry of Education), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
| | - Di Cheng
- Department of Physics and Astronomy, Iowa State University and Ames Laboratory-USDOE, Ames, IA 50011, USA
| | - Xing Chen
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Cyrus Tang Center for Sensor Materials and Application, Zhejiang University, Hangzhou 310027, China; Center of Electron Microscope, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Wei Li
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Cyrus Tang Center for Sensor Materials and Application, Zhejiang University, Hangzhou 310027, China
| | - Zhaohui Ren
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Cyrus Tang Center for Sensor Materials and Application, Zhejiang University, Hangzhou 310027, China.
| | - Jigang Wang
- Department of Physics and Astronomy, Iowa State University and Ames Laboratory-USDOE, Ames, IA 50011, USA.
| | - He Tian
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Cyrus Tang Center for Sensor Materials and Application, Zhejiang University, Hangzhou 310027, China; Center of Electron Microscope, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China.
| | - Ze Zhang
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Cyrus Tang Center for Sensor Materials and Application, Zhejiang University, Hangzhou 310027, China; Center of Electron Microscope, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Gaorong Han
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Cyrus Tang Center for Sensor Materials and Application, Zhejiang University, Hangzhou 310027, China.
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17
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Spectral weight reduction of two-dimensional electron gases at oxide surfaces across the ferroelectric transition. Sci Rep 2020; 10:16834. [PMID: 33033329 PMCID: PMC7545169 DOI: 10.1038/s41598-020-73657-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 09/02/2020] [Indexed: 11/11/2022] Open
Abstract
The discovery of a two-dimensional electron gas (2DEG) at the \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {LaAlO}_3/\hbox {SrTiO}_3$$\end{document}LaAlO3/SrTiO3 interface has set a new platform for all-oxide electronics which could potentially exhibit the interplay among charge, spin, orbital, superconductivity, ferromagnetism and ferroelectricity. In this work, by using angle-resolved photoemission spectroscopy and conductivity measurement, we found the reduction of 2DEGs and the changes of the conductivity nature of some ferroelectric oxides including insulating Nb-lightly-substituted \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {KTaO}_3$$\end{document}KTaO3, \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {BaTiO}_3$$\end{document}BaTiO3 (BTO) and (Ca,Zr)-doped BTO across paraelectric-ferroelectric transition. We propose that these behaviours could be due to the increase of space-charge screening potential at the 2DEG/ferroelectric regions which is a result of the realignment of ferroelectric polarisation upon light irradiation. This finding suggests an opportunity for controlling the 2DEG at a bare oxide surface (instead of interfacial system) by using both light and ferroelectricity.
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18
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The emergence of magnetic ordering at complex oxide interfaces tuned by defects. Nat Commun 2020; 11:3650. [PMID: 32686663 PMCID: PMC7371687 DOI: 10.1038/s41467-020-17377-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 06/27/2020] [Indexed: 11/08/2022] Open
Abstract
Complex oxides show extreme sensitivity to structural distortions and defects, and the intricate balance of competing interactions which emerge at atomically defined interfaces may give rise to unexpected physics. In the interfaces of non-magnetic complex oxides, one of the most intriguing properties is the emergence of magnetism which is sensitive to chemical defects. Particularly, it is unclear which defects are responsible for the emergent magnetic interfaces. Here, we show direct and clear experimental evidence, supported by theoretical explanation, that the B-site cation stoichiometry is crucial for the creation and control of magnetism at the interface between non-magnetic ABO3-perovskite oxides, LaAlO3 and SrTiO3. We find that consecutive defect formation, driven by atomic charge compensation, establishes the formation of robust perpendicular magnetic moments at the interface. Our observations propose a route to tune these emerging magnetoelectric structures, which are strongly coupled at the polar-nonpolar complex oxide interfaces.
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19
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Tuvia G, Frenkel Y, Rout PK, Silber I, Kalisky B, Dagan Y. Ferroelectric Exchange Bias Affects Interfacial Electronic States. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2000216. [PMID: 32510654 DOI: 10.1002/adma.202000216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 04/20/2020] [Indexed: 06/11/2023]
Abstract
In polar oxide interfaces phenomena such as superconductivity, magnetism, 1D conductivity, and quantum Hall states can emerge at the polar discontinuity. Combining controllable ferroelectricity at such interfaces can affect the superconducting properties and sheds light on the mutual effects between the polar oxide and the ferroelectric oxide. Here, the interface between the polar oxide LaAlO3 and the ferroelectric Ca-doped SrTiO3 is studied by means of electrical transport combined with local imaging of the current flow with the use of scanning a superconducting quantum interference device (SQUID). Anomalous behavior of the interface resistivity is observed at low temperatures. The scanning SQUID maps of the current flow suggest that this behavior originates from an intrinsic bias induced by the polar LaAlO3 layer. Such intrinsic bias combined with ferroelectricity can constrain the possible structural domain tiling near the interface. The use of this intrinsic bias is recommended as a method of controlling and tuning the initial state of ferroelectric materials by the design of the polar structure. The hysteretic dependence of the normal and the superconducting state properties on gate voltage can be utilized in multifaceted controllable memory devices.
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Affiliation(s)
- Gal Tuvia
- Raymond and Beverly Sackler School of Physics, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Yiftach Frenkel
- Department of Physics and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Prasanna K Rout
- Raymond and Beverly Sackler School of Physics, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Itai Silber
- Raymond and Beverly Sackler School of Physics, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Beena Kalisky
- Department of Physics and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Yoram Dagan
- Raymond and Beverly Sackler School of Physics, Tel Aviv University, Tel Aviv, 6997801, Israel
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20
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Zhang J, Zhang H, Zhang H, Ma Y, Chen X, Meng F, Qi S, Chen Y, Hu F, Zhang Q, Liu B, Shen B, Zhao W, Han W, Sun J. Long-Range Magnetic Order in Oxide Quantum Wells Hosting Two-Dimensional Electron Gases. ACS APPLIED MATERIALS & INTERFACES 2020; 12:28775-28782. [PMID: 32459951 DOI: 10.1021/acsami.0c05332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
To incorporate spintronics functionalities into two-dimensional devices, it is strongly desired to get two-dimensional electron gases (2DEGs) with high spin polarization. Unfortunately, the magnetic characteristics of the typical 2DEG at the LaAlO3/SrTiO3 interface are very weak due to the nonmagnetic character of SrTiO3 and LaAlO3. While most of the previous works focused on perovskite oxides, here, we extended the exploration for magnetic 2DEG beyond the scope of perovskite combinations, composing 2DEG with SrTiO3 and NaCl-structured EuO that owns a large saturation magnetization and a fairly high Curie temperature. We obtained the 2DEGs that show long-range magnetic order and thus unusual behaviors marked by isotropic butterfly shaped magnetoresistance and remarkable anomalous Hall effect. We found evidence for the presence of more conductive domain walls than elsewhere in the oxide layer where the 2DEG resides. More than that, a relation between interfacial magnetism and carrier density is established. On this basis, the intermediate magnetic states between short-range and long-range ordered states can be achieved. The present work provides guidance for the design of high-performance magnetic 2DEGs.
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Affiliation(s)
- Jine Zhang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Hui Zhang
- Fert Beijing Institute, School of Microelectronics, Beijing Advanced Innovation Center for Big Data and Brain Computing, Beihang University, Beijing 100191, People's Republic of China
| | - Hongrui Zhang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Yang Ma
- International Centre for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
- Collaborative Innovation Centre of Quantum Matter, Beijing 100871, People's Republic of China
| | - Xiaobing Chen
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Fanqi Meng
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Shaojin Qi
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Yuansha Chen
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Fengxia Hu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, People's Republic of China
| | - Qinghua Zhang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Banggui Liu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Baogen Shen
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, People's Republic of China
| | - Weisheng Zhao
- Fert Beijing Institute, School of Microelectronics, Beijing Advanced Innovation Center for Big Data and Brain Computing, Beihang University, Beijing 100191, People's Republic of China
| | - Wei Han
- International Centre for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
- Collaborative Innovation Centre of Quantum Matter, Beijing 100871, People's Republic of China
| | - Jirong Sun
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, People's Republic of China
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21
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Zeeshan HM, Butt MK, Iqbal MA, Wang S, Ren L, Jin K. Revealing the Photocharge-Transfer Mechanism at Manganite-Buffered LaAlO 3/SrTiO 3 Interfaces by Giant Photoresponse. ACS APPLIED MATERIALS & INTERFACES 2020; 12:11197-11203. [PMID: 32028768 DOI: 10.1021/acsami.9b22162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The photoinduced phase transition at complex oxides remains one of the very important issues because of the emergent physics and potential applications. In particular, the mechanism of charge transfer at interfaces under irradiation is challenging. Herein, the photoinduced properties of manganite-buffered LaAlO3/SrTiO3 interfaces with different thicknesses of the buffer layer are systematically investigated. The giant photoresponse is observed, and its relative change in resistance is about 6.24 × 106% at T = 20 K for the sample with a buffer layer thickness of 4.8 nm. Moreover, the transition temperature is enhanced by increasing the thickness of the buffer layer. More importantly, the dead layer effect at the interfaces has been suppressed by using light. All these results are attributed to the charge transfer because of the octahedral tilting at low temperatures and provide a new kind of oxide-based optical devices, such as ultraviolet detectors. This piece of work will pave the way toward two-dimensional electron gas-based optoelectronic devices.
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Affiliation(s)
- Hafiz M Zeeshan
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties and MOE Key Laboratory of Materials Physics and Chemistry, School of Science, Northwestern Polytechnical University, Xi'an 710072, China
| | - Mehwish K Butt
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties and MOE Key Laboratory of Materials Physics and Chemistry, School of Science, Northwestern Polytechnical University, Xi'an 710072, China
| | - Muhammad A Iqbal
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties and MOE Key Laboratory of Materials Physics and Chemistry, School of Science, Northwestern Polytechnical University, Xi'an 710072, China
| | - Shuanhu Wang
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties and MOE Key Laboratory of Materials Physics and Chemistry, School of Science, Northwestern Polytechnical University, Xi'an 710072, China
| | - Lixia Ren
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties and MOE Key Laboratory of Materials Physics and Chemistry, School of Science, Northwestern Polytechnical University, Xi'an 710072, China
| | - Kexin Jin
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties and MOE Key Laboratory of Materials Physics and Chemistry, School of Science, Northwestern Polytechnical University, Xi'an 710072, China
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22
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Wadehra N, Tomar R, Varma RM, Gopal RK, Singh Y, Dattagupta S, Chakraverty S. Planar Hall effect and anisotropic magnetoresistance in polar-polar interface of LaVO 3-KTaO 3 with strong spin-orbit coupling. Nat Commun 2020; 11:874. [PMID: 32054860 PMCID: PMC7018836 DOI: 10.1038/s41467-020-14689-z] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 01/23/2020] [Indexed: 11/26/2022] Open
Abstract
Among the perovskite oxide family, KTaO3 (KTO) has recently attracted considerable interest as a possible system for the realization of the Rashba effect. In this work, we report a novel conducting interface by placing KTO with another insulator, LaVO3 (LVO) and report planar Hall effect (PHE) and anisotropic magnetoresistance (AMR) measurements. This interface exhibits a signature of strong spin-orbit coupling. Our experimental observations of two fold AMR and PHE at low magnetic fields (B) is similar to those obtained for topological systems and can be intuitively understood using a phenomenological theory for a Rashba spin-split system. Our experimental data show a B2 dependence of AMR and PHE at low magnetic fields that could also be explained based on our model. At high fields (~8 T), we see a two fold to four fold transition in the AMR that could not be explained using only Rashba spin-split energy spectra. Two dimensional electron gas (2DEG) at oxide interfaces is promising in modern electronic devices. Here, Wadehra et al. realize 2DEG at a novel interface composed of LaVO3 and KTaO3, where strong spin-orbit coupling and relativistic nature of the electrons in the 2DEG, leading to anisotropic magnetoresistance and planar Hall effect.
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Affiliation(s)
- Neha Wadehra
- Nanoscale Physics and Device Laboratory, Institute of Nano Science and Technology, Phase-10, Sector-64, Mohali, Punjab, 160062, India
| | - Ruchi Tomar
- Nanoscale Physics and Device Laboratory, Institute of Nano Science and Technology, Phase-10, Sector-64, Mohali, Punjab, 160062, India
| | - Rahul Mahavir Varma
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangaluru, Karnataka, 560012, India
| | - R K Gopal
- Indian Institute of Science Education and Research Mohali, Knowledge City, Sector-81, SAS Nagar, Manauli, 140306, India
| | - Yogesh Singh
- Indian Institute of Science Education and Research Mohali, Knowledge City, Sector-81, SAS Nagar, Manauli, 140306, India
| | - Sushanta Dattagupta
- Bose Institute, P-1/12, CIT Rd, Scheme VIIM, Kankurgachi, Kolkata, West Bengal, 700054, India
| | - S Chakraverty
- Nanoscale Physics and Device Laboratory, Institute of Nano Science and Technology, Phase-10, Sector-64, Mohali, Punjab, 160062, India.
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23
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Zhang L, Zheng D, Fan L, Wang J, Kim M, Wang J, Wang H, Xing X, Tian J, Chen J. Controllable Ferromagnetism in Super-tetragonal PbTiO 3 through Strain Engineering. NANO LETTERS 2020; 20:881-886. [PMID: 31887059 DOI: 10.1021/acs.nanolett.9b03472] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The coupling strain in nanoscale systems can achieve control of the physical properties in functional materials, such as ferromagnets, ferroelectrics, and superconductors. Here, we directly demonstrate the atomic-scale structure of super-tetragonal PbTiO3 nanocomposite epitaxial thin films, including the extraordinary coupling of strain transition and the existence of the oxygen vacancies. Large strain gradients, both longitudinal and transverse (∼3 × 107 m-1), have been observed. The original non-magnetic ferroelectric composites notably evoke ferromagnetic properties, derived from the combination of Ti3+ and oxygen vacancies. The saturation ferromagnetic moment can be controlled by the strain of both the interphase and substrate, optimized to a high value of ∼55 emu/cc in 10-nm thick nanocomposite epitaxial thin films on the LaAlO3 substrate. Strain engineering provides a route to explore multiferroic systems in conventional non-magnetic ferroelectric oxides and to create functional data storage devices from both ferroelectrics and ferromagnetics.
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Affiliation(s)
- Linxing Zhang
- Institute for Advanced Materials and Technology , University of Science and Technology Beijing , Beijing 100083 , China
| | - Dongxing Zheng
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Processing Technology, School of Science , Tianjin University , Tianjin 300350 , China
| | - Longlong Fan
- College of Physics and Materials Science , Tianjin Normal University , Tianjin 300387 , China
| | - Jinguo Wang
- Department of Materials Science and Engineering , University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Moon Kim
- Department of Materials Science and Engineering , University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Jiaou Wang
- Institute of High Energy Physics , Chinese Academy of Sciences , Beijing 100049 , China
| | - Huanhua Wang
- Institute of High Energy Physics , Chinese Academy of Sciences , Beijing 100049 , China
| | - Xianran Xing
- Beijing Advanced Innovation Center for Materials Genome Engineering, Department of Physical Chemistry , University of Science and Technology Beijing , Beijing 100083 , China
| | - Jianjun Tian
- Institute for Advanced Materials and Technology , University of Science and Technology Beijing , Beijing 100083 , China
| | - Jun Chen
- School of Mathematics and Physics , University of Science and Technology Beijing , Beijing 100083 , China
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24
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Yin C, Smink AEM, Leermakers I, Tang LMK, Lebedev N, Zeitler U, van der Wiel WG, Hilgenkamp H, Aarts J. Electron Trapping Mechanism in LaAlO_{3}/SrTiO_{3} Heterostructures. PHYSICAL REVIEW LETTERS 2020; 124:017702. [PMID: 31976734 DOI: 10.1103/physrevlett.124.017702] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Revised: 09/13/2019] [Indexed: 06/10/2023]
Abstract
In LaAlO_{3}/SrTiO_{3} heterostructures, a still poorly understood phenomenon is that of electron trapping in back-gating experiments. Here, by combining magnetotransport measurements and self-consistent Schrödinger-Poisson calculations, we obtain an empirical relation between the amount of trapped electrons and the gate voltage. The amount of trapped electrons decays exponentially away from the interface. However, contrary to earlier observations, we find that the Fermi level remains well within the quantum well. The enhanced trapping of electrons induced by the gate voltage can therefore not be explained by a thermal escape mechanism. Further gate sweeping experiments strengthen that conclusion. We propose a new mechanism which involves the electromigration and clustering of oxygen vacancies in SrTiO_{3} and argue that such electron trapping is a universal phenomenon in SrTiO_{3}-based two-dimensional electron systems.
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Affiliation(s)
- Chunhai Yin
- Huygens-Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
| | - Alexander E M Smink
- MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Inge Leermakers
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
| | - Lucas M K Tang
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
| | - Nikita Lebedev
- Huygens-Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
| | - Uli Zeitler
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
| | - Wilfred G van der Wiel
- MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Hans Hilgenkamp
- MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Jan Aarts
- Huygens-Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
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25
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Li W, Zhu B, He Q, Borisevich AY, Yun C, Wu R, Lu P, Qi Z, Wang Q, Chen A, Wang H, Cavill SA, Zhang KHL, MacManus‐Driscoll JL. Interface Engineered Room-Temperature Ferromagnetic Insulating State in Ultrathin Manganite Films. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:1901606. [PMID: 31921553 PMCID: PMC6947487 DOI: 10.1002/advs.201901606] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 10/23/2019] [Indexed: 06/10/2023]
Abstract
Ultrathin epitaxial films of ferromagnetic insulators (FMIs) with Curie temperatures near room temperature are critically needed for use in dissipationless quantum computation and spintronic devices. However, such materials are extremely rare. Here, a room-temperature FMI is achieved in ultrathin La0.9Ba0.1MnO3 films grown on SrTiO3 substrates via an interface proximity effect. Detailed scanning transmission electron microscopy images clearly demonstrate that MnO6 octahedral rotations in La0.9Ba0.1MnO3 close to the interface are strongly suppressed. As determined from in situ X-ray photoemission spectroscopy, O K-edge X-ray absorption spectroscopy, and density functional theory, the realization of the FMI state arises from a reduction of Mn eg bandwidth caused by the quenched MnO6 octahedral rotations. The emerging FMI state in La0.9Ba0.1MnO3 together with necessary coherent interface achieved with the perovskite substrate gives very high potential for future high performance electronic devices.
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Affiliation(s)
- Weiwei Li
- Department of Materials Science and MetallurgyUniversity of Cambridge27 Charles Babbage RoadCambridgeCB3 0FSUK
| | - Bonan Zhu
- Department of Materials Science and MetallurgyUniversity of Cambridge27 Charles Babbage RoadCambridgeCB3 0FSUK
| | - Qian He
- Cardiff Catalysis InstituteSchool of ChemistryCardiff UniversityMain Building, Park PlaceCardiffCF10 3ATUK
| | - Albina Y. Borisevich
- Center for Nanophase Materials SciencesOak Ridge National LaboratoryOak RidgeTN37831USA
| | - Chao Yun
- Department of Materials Science and MetallurgyUniversity of Cambridge27 Charles Babbage RoadCambridgeCB3 0FSUK
| | - Rui Wu
- Department of Materials Science and MetallurgyUniversity of Cambridge27 Charles Babbage RoadCambridgeCB3 0FSUK
| | - Ping Lu
- Sandia National LaboratoryAlbuquerqueNM87185USA
| | - Zhimin Qi
- School of Materials EngineeringPurdue UniversityWest LafayetteIN47907USA
| | - Qiang Wang
- Department of Physics and AstronomyWest Virginia UniversityMorgantownWV26506USA
| | - Aiping Chen
- Center for Integrated NanotechnologiesLos Alamos National LaboratoryLos AlamosNM87545USA
| | - Haiyan Wang
- School of Materials EngineeringPurdue UniversityWest LafayetteIN47907USA
| | - Stuart A. Cavill
- Department of PhysicsUniversity of YorkYorkYO10 5DDUK
- Diamond Light SourceDidcotOX11 0DEUK
| | - Kelvin H. L. Zhang
- State Key Laboratory of Physical Chemistry of Solid SurfacesCollege of Chemistry and Chemical EngineeringXiamen UniversityXiamen361005China
| | - Judith L. MacManus‐Driscoll
- Department of Materials Science and MetallurgyUniversity of Cambridge27 Charles Babbage RoadCambridgeCB3 0FSUK
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26
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Nakano M, Wang Y, Yoshida S, Matsuoka H, Majima Y, Ikeda K, Hirata Y, Takeda Y, Wadati H, Kohama Y, Ohigashi Y, Sakano M, Ishizaka K, Iwasa Y. Intrinsic 2D Ferromagnetism in V 5Se 8 Epitaxial Thin Films. NANO LETTERS 2019; 19:8806-8810. [PMID: 31714089 DOI: 10.1021/acs.nanolett.9b03614] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The discoveries of intrinsic ferromagnetism in atomically thin van der Waals crystals have opened a new research field enabling fundamental studies on magnetism at two-dimensional (2D) limit as well as development of magnetic van der Waals heterostructures. Currently, a variety of 2D ferromagnetism has been explored mainly by mechanically exfoliating "originally ferromagnetic (FM)" van der Waals crystals, while a bottom-up approach by thin-film growth technique has demonstrated emergent 2D ferromagnetism in a variety of "originally non-FM" van der Waals materials. Here we demonstrate that V5Se8 epitaxial thin films grown by molecular-beam epitaxy exhibit emergent 2D ferromagnetism with intrinsic spin polarization of the V 3d electrons despite that the bulk counterpart is "originally antiferromagnetic". Moreover, thickness-dependence measurements reveal that this newly developed 2D ferromagnet could be classified as an itinerant 2D Heisenberg ferromagnet with weak magnetic anisotropy, broadening a lineup of 2D magnets to those potentially beneficial for future spintronics applications.
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Affiliation(s)
- Masaki Nakano
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
- RIKEN Center for Emergent Matter Science , Wako 351-0198 , Japan
| | - Yue Wang
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
| | - Satoshi Yoshida
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
| | - Hideki Matsuoka
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
| | - Yuki Majima
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
| | - Keisuke Ikeda
- Department of Physics , the University of Tokyo , Tokyo 113-0033 , Japan
| | - Yasuyuki Hirata
- Department of Physics , the University of Tokyo , Tokyo 113-0033 , Japan
- The Institute for Solid State Physics , the University of Tokyo , Kashiwa 227-8581 , Japan
| | - Yukiharu Takeda
- Materials Sciences Research Center , Japan Atomic Energy Agency , Koto City 679-5148 , Hyogo , Japan
| | - Hiroki Wadati
- Department of Physics , the University of Tokyo , Tokyo 113-0033 , Japan
- The Institute for Solid State Physics , the University of Tokyo , Kashiwa 227-8581 , Japan
| | - Yoshimitsu Kohama
- The Institute for Solid State Physics , the University of Tokyo , Kashiwa 227-8581 , Japan
| | - Yuta Ohigashi
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
| | - Masato Sakano
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
| | - Kyoko Ishizaka
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
- RIKEN Center for Emergent Matter Science , Wako 351-0198 , Japan
| | - Yoshihiro Iwasa
- Quantum-Phase Electronics Center and Department of Applied Physics , the University of Tokyo , Tokyo 113-8656 , Japan
- RIKEN Center for Emergent Matter Science , Wako 351-0198 , Japan
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27
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Wang X, Pan Z, Chu X, Huang K, Cong Y, Cao R, Sarangi R, Li L, Li G, Feng S. Atomic‐Scale Insights into Surface Lattice Oxygen Activation at the Spinel/Perovskite interface of Co
3
O
4
/La
0.3
Sr
0.7
CoO
3. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201905543] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Xiyang Wang
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun 130012 P. R. China
| | - Ziye Pan
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun 130012 P. R. China
| | - Xuefeng Chu
- Jilin Provincial Key Laboratory of Architectural Electricity & Comprehensive Energy Saving School of Electrical and Electronic Information Engineering Jilin Jianzhu University Changchun 130118 P. R. China
| | - Keke Huang
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun 130012 P. R. China
| | - Yingge Cong
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun 130012 P. R. China
| | - Rui Cao
- Stanford Synchrotron Radiation Lightsource SLAC National Accelerator Laboratory Menlo Park CA 94025 USA
| | - Ritimukta Sarangi
- Stanford Synchrotron Radiation Lightsource SLAC National Accelerator Laboratory Menlo Park CA 94025 USA
| | - Liping Li
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun 130012 P. R. China
| | - Guangshe Li
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun 130012 P. R. China
| | - Shouhua Feng
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun 130012 P. R. China
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28
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Wang X, Pan Z, Chu X, Huang K, Cong Y, Cao R, Sarangi R, Li L, Li G, Feng S. Atomic‐Scale Insights into Surface Lattice Oxygen Activation at the Spinel/Perovskite interface of Co
3
O
4
/La
0.3
Sr
0.7
CoO
3. Angew Chem Int Ed Engl 2019; 58:11720-11725. [DOI: 10.1002/anie.201905543] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2019] [Indexed: 01/01/2023]
Affiliation(s)
- Xiyang Wang
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun 130012 P. R. China
| | - Ziye Pan
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun 130012 P. R. China
| | - Xuefeng Chu
- Jilin Provincial Key Laboratory of Architectural Electricity & Comprehensive Energy Saving School of Electrical and Electronic Information Engineering Jilin Jianzhu University Changchun 130118 P. R. China
| | - Keke Huang
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun 130012 P. R. China
| | - Yingge Cong
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun 130012 P. R. China
| | - Rui Cao
- Stanford Synchrotron Radiation Lightsource SLAC National Accelerator Laboratory Menlo Park CA 94025 USA
| | - Ritimukta Sarangi
- Stanford Synchrotron Radiation Lightsource SLAC National Accelerator Laboratory Menlo Park CA 94025 USA
| | - Liping Li
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun 130012 P. R. China
| | - Guangshe Li
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun 130012 P. R. China
| | - Shouhua Feng
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun 130012 P. R. China
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29
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Wang H, Chi X, Liu Z, Yoong H, Tao L, Xiao J, Guo R, Wang J, Dong Z, Yang P, Sun CJ, Li C, Yan X, Wang J, Chow GM, Tsymbal EY, Tian H, Chen J. Atomic-Scale Control of Magnetism at the Titanite-Manganite Interfaces. NANO LETTERS 2019; 19:3057-3065. [PMID: 30964306 DOI: 10.1021/acs.nanolett.9b00441] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Complex oxide thin-film heterostructures often exhibit magnetic properties different from those known for bulk constituents. This is due to the altered local structural and electronic environment at the interfaces, which affects the exchange coupling and magnetic ordering. The emergent magnetism at oxide interfaces can be controlled by ferroelectric polarization and has a strong effect on spin-dependent transport properties of oxide heterostructures, including magnetic and ferroelectric tunnel junctions. Here, using prototype La2/3Sr1/3MnO3/BaTiO3 heterostructures, we demonstrate that ferroelectric polarization of BaTiO3 controls the orbital hybridization and magnetism at heterointerfaces. We observe changes in the enhanced orbital occupancy and significant charge redistribution across the heterointerfaces, affecting the spin and orbital magnetic moments of the interfacial Mn and Ti atoms. Importantly, we find that the exchange coupling between Mn and Ti atoms across the interface is tuned by ferroelectric polarization from ferromagnetic to antiferromagnetic. Our findings provide a viable route to electrically control complex magnetic configurations at artificial multiferroic interfaces, taking a step toward low-power spintronics.
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Affiliation(s)
- Han Wang
- Department of Materials Science and Engineering , National University of Singapore , 117575 Singapore
| | - Xiao Chi
- Department of Physics , National University of Singapore , 2 Science Drive 3 , 117542 Singapore
- Singapore Synchrotron Light Source (SSLS) , National University of Singapore , 117603 Singapore
| | - ZhongRan Liu
- Center of Electron Microscope, State Key Laboratory of Silicon Materials, School of Materials Science and Engineering , Zhejiang University , Hangzhou 310027 , China
| | - HerngYau Yoong
- Department of Materials Science and Engineering , National University of Singapore , 117575 Singapore
| | - LingLing Tao
- Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience , University of Nebraska , Lincoln , Nebraska 68588-0299 , United States
| | - JuanXiu Xiao
- Department of Materials Science and Engineering , National University of Singapore , 117575 Singapore
| | - Rui Guo
- Department of Materials Science and Engineering , National University of Singapore , 117575 Singapore
| | - JingXian Wang
- School of Materials Science and Engineering , Nanyang Technological University , 639798 Singapore
| | - ZhiLi Dong
- School of Materials Science and Engineering , Nanyang Technological University , 639798 Singapore
| | - Ping Yang
- Singapore Synchrotron Light Source (SSLS) , National University of Singapore , 117603 Singapore
| | - Cheng-Jun Sun
- Advanced Photon Source , Argonne National Laboratory , Argonne , Illinois 60439 , United States
| | - ChangJian Li
- Department of Materials Science and Engineering , National University of Singapore , 117575 Singapore
| | - XiaoBing Yan
- College of Electron and Information Engineering , Hebei University , Baoding 071002 , China
| | - John Wang
- Department of Materials Science and Engineering , National University of Singapore , 117575 Singapore
| | - Gan Moog Chow
- Department of Materials Science and Engineering , National University of Singapore , 117575 Singapore
| | - Evgeny Y Tsymbal
- Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience , University of Nebraska , Lincoln , Nebraska 68588-0299 , United States
| | - He Tian
- Center of Electron Microscope, State Key Laboratory of Silicon Materials, School of Materials Science and Engineering , Zhejiang University , Hangzhou 310027 , China
| | - Jingsheng Chen
- Department of Materials Science and Engineering , National University of Singapore , 117575 Singapore
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30
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Lee SR, Baasandorj L, Chang JW, Hwang IW, Kim JR, Kim JG, Ko KT, Shim SB, Choi MW, You M, Yang CH, Kim J, Song J. First Observation of Ferroelectricity in ∼1 nm Ultrathin Semiconducting BaTiO 3 Films. NANO LETTERS 2019; 19:2243-2250. [PMID: 30860385 DOI: 10.1021/acs.nanolett.8b04326] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The requirements of multifunctionality in thin-film systems have led to the discovery of unique physical properties and degrees of freedom, which exist only in film forms. With progress in growth techniques, one can decrease the film thickness to the scale of a few nanometers (∼nm), where its unique physical properties are still pronounced. Among advanced ultrathin film systems, ferroelectrics have generated tremendous interest. As a prototype ferroelectric, the electrical properties of BaTiO3 (BTO) films have been extensively studied, and it has been theoretically predicted that ferroelectricity sustains down to ∼nm thick films. However, efforts toward determining the minimum thickness for ferroelectric films have been hindered by practical issues surrounding large leakage currents. In this study, we used ∼nm thick BTO films, exhibiting semiconducting characteristics, grown on a LaAlO3/SrTiO3 (LAO/STO) heterostructure. In particular, we utilized two-dimensional electron gas at the LAO/STO heterointerface as the bottom electrode in these capacitor junctions. We demonstrate that the BTO film exhibits ferroelectricity at room temperature, even when it is only ∼2 unit-cells thick, and the total thickness of the capacitor junction can be reduced to less than ∼4 nm. Observation of ferroelectricity in ultrathin semiconducting films and the resulting shrunken capacitor thickness will expand the applicability of ferroelectrics in the next generation of functional devices.
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Affiliation(s)
- Seung Ran Lee
- Korea Research Institute of Standards and Science , Daejeon 34113 , Republic of Korea
- Center for Correlated Electron Systems, Institute for Basic Science (IBS) & Department of Physics and Astronomy , Seoul National University , Seoul 08826 , Republic of Korea
| | | | - Jung Won Chang
- Department of Display and Semiconductor Physics , Korea University , Sejong 30019 , Republic of Korea
| | - In Woong Hwang
- Department of Physics , Chungnam National University , Daejeon 34134 , Republic of Korea
| | - Jeong Rae Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS) & Department of Physics and Astronomy , Seoul National University , Seoul 08826 , Republic of Korea
| | | | | | - Seung Bo Shim
- Korea Research Institute of Standards and Science , Daejeon 34113 , Republic of Korea
| | - Min Woo Choi
- Department of Physics , Chungnam National University , Daejeon 34134 , Republic of Korea
| | - Mujin You
- Department of Physics , KAIST , Daejeon 34141 , Republic of Korea
| | - Chan-Ho Yang
- Department of Physics , KAIST , Daejeon 34141 , Republic of Korea
| | - Jinhee Kim
- Korea Research Institute of Standards and Science , Daejeon 34113 , Republic of Korea
| | - Jonghyun Song
- Department of Physics , Chungnam National University , Daejeon 34134 , Republic of Korea
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31
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Huang Z, Renshaw Wang X, Rusydi A, Chen J, Yang H, Venkatesan T. Interface Engineering and Emergent Phenomena in Oxide Heterostructures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1802439. [PMID: 30133012 DOI: 10.1002/adma.201802439] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 07/06/2018] [Indexed: 06/08/2023]
Abstract
Complex oxide interfaces have mesmerized the scientific community in the last decade due to the possibility of creating tunable novel multifunctionalities, which are possible owing to the strong interaction among charge, spin, orbital, and structural degrees of freedom. Artificial interfacial modifications, which include defects, formal polarization, structural symmetry breaking, and interlayer interaction, have led to novel properties in various complex oxide heterostructures. These emergent phenomena not only serve as a platform for investigating strong electronic correlations in low-dimensional systems but also provide potentials for exploring next-generation electronic devices with high functionality. Herein, some recently developed strategies in engineering functional oxide interfaces and their emergent properties are reviewed.
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Affiliation(s)
- Zhen Huang
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Xiao Renshaw Wang
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Andrivo Rusydi
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Jingsheng Chen
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Hyunsoo Yang
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Thirumalai Venkatesan
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
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32
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Zhang H, Yun Y, Zhang X, Zhang H, Ma Y, Yan X, Wang F, Li G, Li R, Khan T, Chen Y, Liu W, Hu F, Liu B, Shen B, Han W, Sun J. High-Mobility Spin-Polarized Two-Dimensional Electron Gases at EuO/KTaO_{3} Interfaces. PHYSICAL REVIEW LETTERS 2018; 121:116803. [PMID: 30265094 DOI: 10.1103/physrevlett.121.116803] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 05/16/2018] [Indexed: 06/08/2023]
Abstract
Two-dimensional electron gases (2DEGs) at oxide interfaces, which provide unique playgrounds for emergent phenomena, have attracted increasing attention in recent years. While most of the previous works focused on the 2DEGs at LaAlO_{3}/SrTiO_{3} interfaces, here we report on a new kind of 2DEGs formed between a magnetic insulator EuO and a high-k perovskite KTaO_{3}. The 2DEGs are not only highly conducting, with a maximal Hall mobility of 111.6 cm^{2}/V s at 2 K, but also well spin polarized, showing strongly hysteretic magnetoresistance up to 25 K and well-defined anomalous Hall effect up to 70 K. Moreover, unambiguous correspondences between the hysteretic behaviors of 2DEGs and the EuO layer are captured, suggesting the proximity effect of the latter on the former. This is confirmed by the results of density-functional theory calculations: Through interlayer exchange, EuO drives the neighboring TaO_{2} layer into a ferromagnetic state. The present work opens new avenues for the exploration for high performance spin-polarized 2DEGs at oxide interfaces.
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Affiliation(s)
- Hongrui Zhang
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Yu Yun
- International Centre for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
- Collaborative Innovation Centre of Quantum Matter, Beijing 100871, People's Republic of China
| | - Xuejing Zhang
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Hui Zhang
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Yang Ma
- International Centre for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
- Collaborative Innovation Centre of Quantum Matter, Beijing 100871, People's Republic of China
| | - Xi Yan
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Fei Wang
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, People's Republic of China
| | - Gang Li
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Rui Li
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Tahira Khan
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Yuansha Chen
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Wei Liu
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, People's Republic of China
| | - Fengxia Hu
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Banggui Liu
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Baogen Shen
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Wei Han
- International Centre for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
- Collaborative Innovation Centre of Quantum Matter, Beijing 100871, People's Republic of China
| | - Jirong Sun
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
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33
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Ortmann JE, Nookala N, He Q, Gao L, Lin C, Posadas AB, Borisevich AY, Belkin MA, Demkov AA. Quantum Confinement in Oxide Heterostructures: Room-Temperature Intersubband Absorption in SrTiO 3/LaAlO 3 Multiple Quantum Wells. ACS NANO 2018; 12:7682-7689. [PMID: 30052026 DOI: 10.1021/acsnano.8b01293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The Si-compatibility of perovskite heterostructures offers the intriguing possibility of producing oxide-based quantum well (QW) optoelectronic devices for use in Si photonics. While the SrTiO3/LaAlO3 (STO/LAO) system has been studied extensively in the hopes of using the interfacial two-dimensional electron gas in Si-integrated electronics, the potential to exploit its giant 2.4 eV conduction band offset in oxide-based QW optoelectronic devices has so far been largely ignored. Here, we demonstrate room-temperature intersubband absorption in STO/LAO QW heterostructures at energies on the order of hundreds of meV, including at energies approaching the critically important telecom wavelength of 1.55 μm. We demonstrate the ability to control the absorption energy by changing the width of the STO well layers by a single unit cell and present theory showing good agreement with experiment. A detailed structural and chemical analysis of the samples via scanning transmission electron microscopy and electron energy loss spectroscopy is presented. This work represents an important proof-of-concept for the use of transition metal oxide QWs in Si-compatible optoelectronic devices.
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Affiliation(s)
- J Elliott Ortmann
- Department of Physics , The University of Texas , Austin , Texas 78712 , United States
| | - Nishant Nookala
- Department of Electrical and Computer Engineering , The University of Texas , Austin , Texas 78712 , United States
- Microelectronics Research Center , The University of Texas at Austin , Austin , Texas 78758 , United States
| | - Qian He
- The Materials Science and Technology Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Lingyuan Gao
- Department of Physics , The University of Texas , Austin , Texas 78712 , United States
| | - Chungwei Lin
- Department of Physics , The University of Texas , Austin , Texas 78712 , United States
- Mitsubishi Electric Research Laboratories , Cambridge , Massachusetts 02139 , United States
| | - Agham B Posadas
- Department of Physics , The University of Texas , Austin , Texas 78712 , United States
| | - Albina Y Borisevich
- The Materials Science and Technology Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Mikhail A Belkin
- Department of Electrical and Computer Engineering , The University of Texas , Austin , Texas 78712 , United States
- Microelectronics Research Center , The University of Texas at Austin , Austin , Texas 78758 , United States
| | - Alexander A Demkov
- Department of Physics , The University of Texas , Austin , Texas 78712 , United States
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34
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Wang Y, Guo H, Zheng Q, Saidi WA, Zhao J. Tuning Solvated Electrons by Polar-Nonpolar Oxide Heterostructure. J Phys Chem Lett 2018; 9:3049-3056. [PMID: 29767527 DOI: 10.1021/acs.jpclett.8b00938] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Solvated electron states at the oxide/aqueous interface represent the lowest energy charge-transfer pathways, thereby playing an important role in photocatalysis and electronic device applications. However, their energies are usually higher than the conduction band minimum (CBM), which makes the solvated electrons difficult to utilize in charge-transfer processes. Thus it is essential to stabilize the energy of the solvated electron states. Taking LaAlO3/SrTiO3 (LAO/STO) oxide heterostructure with H2O-adsorbed monolayer as a prototypical system, we show using DFT and ab initio time-dependent nonadiabatic molecular dynamics simulation that the energy and dynamics of solvated electrons can be tuned by the electric field in the polar-nonpolar oxide heterostructure. In particular, for LAO/STO with p-type interface, the CBM is contributed by the solvated electron state when LAO is thicker than four unit cells. Furthermore, the solvated electron band minimum can be partially occupied when LAO is thicker than eight unit cells. We propose that the tunability of solvated electron states can be achieved on polar-nonpolar oxide heterostructure surfaces as well as on ferroelectric oxides, which is important for charge and proton transfer at oxide/aqueous interfaces.
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Affiliation(s)
- Yanan Wang
- ICQD/Hefei National Laboratory for Physical Sciences at Microscale and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences and Department of Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Hongli Guo
- ICQD/Hefei National Laboratory for Physical Sciences at Microscale and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences and Department of Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
- School of Physics and Technology, Center for Nanoscience and Nanotechnology, and Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education , Wuhan University , Wuhan 430072 , China
| | - Qijing Zheng
- ICQD/Hefei National Laboratory for Physical Sciences at Microscale and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences and Department of Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Wissam A Saidi
- Department of Mechanical Engineering and Materials Science , University of Pittsburgh , Pittsburgh , Pennsylvania 15261 , United States
| | - Jin Zhao
- ICQD/Hefei National Laboratory for Physical Sciences at Microscale and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences and Department of Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
- Department of Physics and Astronomy , University of Pittsburgh , Pittsburgh , Pennsylvania 15260 , United States
- Synergetic Innovation Center of Quantum Information & Quantum Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
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35
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Chi X, Huang Z, Asmara TC, Han K, Yin X, Yu X, Diao C, Yang M, Schmidt D, Yang P, Trevisanutto PE, Whitcher TJ, Venkatesan T, Breese MBH, Rusydi A. Large Enhancement of 2D Electron Gases Mobility Induced by Interfacial Localized Electron Screening Effect. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1707428. [PMID: 29667241 DOI: 10.1002/adma.201707428] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 02/13/2018] [Indexed: 06/08/2023]
Abstract
The interactions between delocalized and localized charges play important roles in correlated electron systems. Here, using a combination of transport measurements, spectroscopic ellipsometry (SE), and X-ray absorption spectroscopy (XAS) supported by theoretical calculations, we reveal the important role of interfacial localized charges and their screening effects in determining the mobility of (La0.3 Sr0.7 )(Al0.65 Ta0.35 )O3 /SrTiO3 (LSAT/SrTiO3 ) interfaces. When the LSAT layer thickness reaches the critical value of 5 uc, the insulating interface abruptly becomes conducting, accompanied by the appearance of a new midgap state. This midgap state emerges at ≈1 eV below the Ti t2g band and shows a strong character of Ti 3dxy - O 2p hybridization. Increasing the LSAT layer from 5 to 18 uc, the number of localized charges increases, resulting in an enhanced screening effect and higher mobile electron mobility. This observation contradicts the traditional semiconductor interface where the localized charges always suppress the carrier mobility. These results demonstrate a new strategy to probe localized charges and mobile electrons in correlated electronic systems and highlight the important role of screening effects from localized charges in improving the mobile electron mobility at complex oxide interfaces.
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Affiliation(s)
- Xiao Chi
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Zhen Huang
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- NUSSNI-NanoCore, National University of Singapore, Singapore, 117576, Singapore
| | - Teguh C Asmara
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- NUSSNI-NanoCore, National University of Singapore, Singapore, 117576, Singapore
| | - Kun Han
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- NUSSNI-NanoCore, National University of Singapore, Singapore, 117576, Singapore
| | - Xinmao Yin
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Xiaojiang Yu
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - Caozheng Diao
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - Ming Yang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117546, Singapore
- Institute of Materials Research and Engineering, A*-STAR, 2 Fusionopolis Way, Singapore, 138634, Singapore
| | - Daniel Schmidt
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - Ping Yang
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - Paolo E Trevisanutto
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - T J Whitcher
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
| | - T Venkatesan
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- NUSSNI-NanoCore, National University of Singapore, Singapore, 117576, Singapore
- National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS), 28 Medical Drive, Singapore, 117456, Singapore
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117583, Singapore
| | - Mark B H Breese
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Andrivo Rusydi
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore, 117603, Singapore
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- NUSSNI-NanoCore, National University of Singapore, Singapore, 117576, Singapore
- National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS), 28 Medical Drive, Singapore, 117456, Singapore
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36
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Yan H, Zhang Z, Wang S, Wei X, Chen C, Jin K. Magnetism Control by Doping in LaAlO 3/SrTiO 3 Heterointerfaces. ACS APPLIED MATERIALS & INTERFACES 2018; 10:14209-14213. [PMID: 29619833 DOI: 10.1021/acsami.8b03275] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Magnetic two-dimensional electron gases at the oxide interfaces are always one of the key issues in spintronics, giving rise to intriguing magnetotransport properties. However, reports about magnetic two-dimensional electron gases remain elusive. Here, we obtain the magnetic order of LaAlO3/SrTiO3 systems by introducing magnetic dopants at the La site. The transport properties with a characteristic of metallic behavior at the interfaces are investigated. More significantly, magnetic-doped samples exhibit obvious magnetic hysteresis loops and the mobility is enhanced. Meanwhile, the photoresponsive experiments are realized by irradiating all samples with a 360 nm light. Compared to magnetism, the effects of dopants on photoresponsive and relaxation properties are negligible because the behavior originates from SrTiO3 substrates. This work paves a way for revealing and better controlling the magnetic properties of oxide heterointerfaces.
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Affiliation(s)
- Hong Yan
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties, School of Science , Northwestern Polytechnical University , Xi'an 710072 , China
| | - Zhaoting Zhang
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties, School of Science , Northwestern Polytechnical University , Xi'an 710072 , China
| | - Shuanhu Wang
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties, School of Science , Northwestern Polytechnical University , Xi'an 710072 , China
| | - Xiangyang Wei
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties, School of Science , Northwestern Polytechnical University , Xi'an 710072 , China
| | - Changle Chen
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties, School of Science , Northwestern Polytechnical University , Xi'an 710072 , China
| | - Kexin Jin
- Shaanxi Key Laboratory of Condensed Matter Structures and Properties, School of Science , Northwestern Polytechnical University , Xi'an 710072 , China
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37
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Lu Y, Wang F, Chen M, Lan Z, Ren Z, Tian H, Yang K. Tuning Interfacial Magnetic Ordering via Polarization Control in Ferroelectric SrTiO 3/PbTiO 3 Heterostructure. ACS APPLIED MATERIALS & INTERFACES 2018; 10:10536-10542. [PMID: 29481040 DOI: 10.1021/acsami.7b19112] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The electromagnetic properties at the interface of heterostructure are sensitive to the interfacial crystal structure and external field. For example, the two-dimensional magnetic states at the interface of LaAlO3/SrTiO3 are discovered and can further be controlled by electric field. Here, we study two types of heterostructures, TiO2/PbTiO3 and SrTiO3/PbTiO3, using first-principle electronic structure calculations. We find that the ferroelectric polarization discontinuity at the interface leads to partially occupied Ti 3d states and the magnetic moments. The magnitude of the magnetic moments and the ground-state magnetic coupling are sensitive to the polarization intensity of PbTiO3. As the ferroelectric polarization of PbTiO3 increases, the two heterostructures show different magnetic ordering that strongly depends on the electron occupation of the Ti t2g orbitals. For the TiO2/PbTiO3 interface, the magnetic moments are mostly contributed by degenerated d yz/d xz orbitals of interfacial Ti atoms and the neighboring interfacial Ti atoms form ferromagnetic coupling. For SrTiO3/PbTiO3 interface, the interfacial magnetic moments are mainly contributed by occupied d xy orbital because of the increased polarization intensity, and as the electron occupation increases, there exists a transition of the magnetic coupling between neighboring Ti atoms from ferromagnetism to antiferromagnetism via the superexchange interaction. Our study suggests that manipulating the polarization intensity is one effective way to control interfacial magnetic ordering in the perovskite oxide heterostructures.
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Affiliation(s)
- Yunhao Lu
- School of Materials Science and Engineering , Zhejiang University , Hangzhou 310027 , China
| | - Fang Wang
- School of Materials Science and Engineering , Zhejiang University , Hangzhou 310027 , China
| | - Miaogen Chen
- Department of Physics , China Jiliang University , Hangzhou 310018 , China
| | - Zhenyun Lan
- School of Materials Science and Engineering , Zhejiang University , Hangzhou 310027 , China
| | - Zhaohui Ren
- School of Materials Science and Engineering , Zhejiang University , Hangzhou 310027 , China
| | - He Tian
- School of Materials Science and Engineering , Zhejiang University , Hangzhou 310027 , China
| | - Kesong Yang
- Department of NanoEngineering , University of California San Diego , 9500 Gilman Drive , Mail Code 0448, La Jolla, San Diego , California 92093-0448 , United States
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38
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Zhang Y, Xie L, Kim J, Stern A, Wang H, Zhang K, Yan X, Li L, Liu H, Zhao G, Chi H, Gadre C, Lin Q, Zhou Y, Uher C, Chen T, Chu YH, Xia J, Wu R, Pan X. Discovery of a magnetic conductive interface in PbZr 0.2Ti 0.8O 3 /SrTiO 3 heterostructures. Nat Commun 2018; 9:685. [PMID: 29449561 PMCID: PMC5814552 DOI: 10.1038/s41467-018-02914-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 01/06/2018] [Indexed: 11/09/2022] Open
Abstract
Emergent physical properties often arise at interfaces of complex oxide heterostructures due to the interplay between various degrees of freedom, especially those with polar discontinuities. It is desirable to explore if these structures may generate pure and controllable spin currents, which are needed to attain unmatched performance and energy efficiency in the next-generation spintronic devices. Here we report the emergence of a spin-polarized two-dimensional electron gas (SP-2DEG) at the interface of two insulators, SrTiO3 and PbZr0.2Ti0.8O3. This SP-2DEG is strongly localized at the interfacial Ti atoms, due to the interplay between Coulomb interaction and band bending, and can be tuned by the ferroelectric polarization. Our findings open a door for engineering ferroelectric/insulator interfaces to create tunable ferroic orders for magnetoelectric device applications and provide opportunities for designing multiferroic materials in heterostructures. Two-dimensional electron gases that form in some complex oxide heterostructures may have useful functional behavior due to the interaction of the parent materials. Here the authors show that PZT/STO interfaces can host a spin-polarized electron gas, even though the bulk materials are nonmagnetic.
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Affiliation(s)
- Yi Zhang
- Department of Chemical Engineering and Materials Science, University of California, Irvine, CA, 92697, USA
| | - Lin Xie
- National Laboratory of Solid State Microstructures and College of Engineering and Applied Sciences, Nanjing University, Nanjing, Jiangsu, 210093, China
| | - Jeongwoo Kim
- Department of Physics and Astronomy, University of California, Irvine, CA, 92697, USA
| | - Alex Stern
- Department of Physics and Astronomy, University of California, Irvine, CA, 92697, USA
| | - Hui Wang
- Department of Physics and Astronomy, University of California, Irvine, CA, 92697, USA
| | - Kui Zhang
- Department of Chemical Engineering and Materials Science, University of California, Irvine, CA, 92697, USA
| | - Xingxu Yan
- Department of Chemical Engineering and Materials Science, University of California, Irvine, CA, 92697, USA
| | - Linze Li
- Department of Chemical Engineering and Materials Science, University of California, Irvine, CA, 92697, USA
| | - Henry Liu
- Department of Materials Science and Engineering, National Chiao Tung University, HsinChu, 30010, Taiwan
| | - Gejian Zhao
- Department of Physics, Arizona State University, Tempe, Arizona, 85287, USA
| | - Hang Chi
- Department of Physics, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Chaitanya Gadre
- Department of Physics and Astronomy, University of California, Irvine, CA, 92697, USA
| | - Qiyin Lin
- Irvine Materials Research Institute, University of California, Irvine, CA, 92697, USA
| | - Yichun Zhou
- School of Materials Science and Engineering, Xiangtan University, Xiangtan, 411105, Hunan, China
| | - Ctirad Uher
- Department of Physics, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Tingyong Chen
- Department of Physics, Arizona State University, Tempe, Arizona, 85287, USA
| | - Ying-Hao Chu
- Department of Materials Science and Engineering, National Chiao Tung University, HsinChu, 30010, Taiwan
| | - Jing Xia
- Department of Physics and Astronomy, University of California, Irvine, CA, 92697, USA
| | - Ruqian Wu
- Department of Physics and Astronomy, University of California, Irvine, CA, 92697, USA
| | - Xiaoqing Pan
- Department of Chemical Engineering and Materials Science, University of California, Irvine, CA, 92697, USA. .,Department of Physics and Astronomy, University of California, Irvine, CA, 92697, USA.
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Pai YY, Tylan-Tyler A, Irvin P, Levy J. Physics of SrTiO 3-based heterostructures and nanostructures: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2018; 81:036503. [PMID: 29424362 DOI: 10.1088/1361-6633/aa892d] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
This review provides a summary of the rich physics expressed within SrTiO3-based heterostructures and nanostructures. The intended audience is researchers who are working in the field of oxides, but also those with different backgrounds (e.g., semiconductor nanostructures). After reviewing the relevant properties of SrTiO3 itself, we will then discuss the basics of SrTiO3-based heterostructures, how they can be grown, and how devices are typically fabricated. Next, we will cover the physics of these heterostructures, including their phase diagram and coupling between the various degrees of freedom. Finally, we will review the rich landscape of quantum transport phenomena, as well as the devices that elicit them.
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Affiliation(s)
- Yun-Yi Pai
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, United States of America. Pittsburgh Quantum Institute, Pittsburgh, PA 15260, United States of America
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40
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Magnetic field observations in CoFeB/Ta layers with 0.67-nm resolution by electron holography. Sci Rep 2017; 7:16598. [PMID: 29209064 PMCID: PMC5717169 DOI: 10.1038/s41598-017-16519-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 11/13/2017] [Indexed: 11/09/2022] Open
Abstract
Nanometre-scale magnetic field distributions in materials such as those at oxide interfaces, in thin layers of spintronics devices, and at boundaries in magnets have become important research targets in materials science and applied physics. Electron holography has advantages in nanometric magnetic field observations, and the realization of aberration correctors has improved its spatial resolution. Here we show the subnanometre magnetic field observations inside a sample at 0.67-nm resolution achieved by an aberration-corrected 1.2-MV holography electron microscope with a pulse magnetization system. A magnetization reduction due to intermixing in a CoFeB/Ta multilayer is analyzed by observing magnetic field and electrostatic potential distributions simultaneously. Our results demonstrate that high-voltage electron holography can be widely applied to pin-point magnetization analysis with structural and composition information in physics, chemistry, and materials science.
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41
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Plumb NC, Radović M. Angle-resolved photoemission spectroscopy studies of metallic surface and interface states of oxide insulators. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:433005. [PMID: 28961143 DOI: 10.1088/1361-648x/aa833f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Over the last decade, conducting states embedded in insulating transition metal oxides (TMOs) have served as gateways to discovering and probing surprising phenomena that can emerge in complex oxides, while also opening opportunities for engineering advanced devices. These states are commonly realized at thin film interfaces, such as the well-known case of LaAlO3 (LAO) grown on SrTiO3 (STO). In recent years, the use of angle-resolved photoemission spectroscopy (ARPES) to investigate the k-space electronic structure of such materials led to the discovery that metallic states can also be formed on the bare surfaces of certain TMOs. In this topical review, we report on recent studies of low-dimensional metallic states confined at insulating oxide surfaces and interfaces as seen from the perspective of ARPES, which provides a direct view of the occupied band structure. While offering a fairly broad survey of progress in the field, we draw particular attention to STO, whose surface is so far the best-studied, and whose electronic structure is probably of the most immediate interest, given the ubiquitous use of STO substrates as the basis for conducting oxide interfaces. The ARPES studies provide crucial insights into the electronic band structure, orbital character, dimensionality/confinement, spin structure, and collective excitations in STO surfaces and related oxide surface/interface systems. The obtained knowledge increases our understanding of these complex materials and gives new perspectives on how to manipulate their properties.
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Affiliation(s)
- Nicholas C Plumb
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
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42
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Chen Z, Chen Z, Liu ZQ, Holtz ME, Li CJ, Wang XR, Lü WM, Motapothula M, Fan LS, Turcaud JA, Dedon LR, Frederick C, Xu RJ, Gao R, N'Diaye AT, Arenholz E, Mundy JA, Venkatesan T, Muller DA, Wang LW, Liu J, Martin LW. Electron Accumulation and Emergent Magnetism in LaMnO_{3}/SrTiO_{3} Heterostructures. PHYSICAL REVIEW LETTERS 2017; 119:156801. [PMID: 29077457 DOI: 10.1103/physrevlett.119.156801] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Indexed: 06/07/2023]
Abstract
Emergent phenomena at polar-nonpolar oxide interfaces have been studied intensely in pursuit of next-generation oxide electronics and spintronics. Here we report the disentanglement of critical thicknesses for electron reconstruction and the emergence of ferromagnetism in polar-mismatched LaMnO_{3}/SrTiO_{3} (001) heterostructures. Using a combination of element-specific x-ray absorption spectroscopy and dichroism, and first-principles calculations, interfacial electron accumulation, and ferromagnetism have been observed within the polar, antiferromagnetic insulator LaMnO_{3}. Our results show that the critical thickness for the onset of electron accumulation is as thin as 2 unit cells (UC), significantly thinner than the observed critical thickness for ferromagnetism of 5 UC. The absence of ferromagnetism below 5 UC is likely induced by electron overaccumulation. In turn, by controlling the doping of the LaMnO_{3}, we are able to neutralize the excessive electrons from the polar mismatch in ultrathin LaMnO_{3} films and thus enable ferromagnetism in films as thin as 3 UC, extending the limits of our ability to synthesize and tailor emergent phenomena at interfaces and demonstrating manipulation of the electronic and magnetic structures of materials at the shortest length scales.
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Affiliation(s)
- Zuhuang Chen
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Zhanghui Chen
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Z Q Liu
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - M E Holtz
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - C J Li
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
- NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore
| | - X Renshaw Wang
- School of Physical and Mathematical Sciences & School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 637371, Singapore
| | - W M Lü
- Condensed Matter Science and Technology Institute, School of Science, Harbin Institute of Technology, Harbin 150081, People's Republic of China
| | - M Motapothula
- NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore
| | - L S Fan
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - J A Turcaud
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - L R Dedon
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - C Frederick
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - R J Xu
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - R Gao
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - A T N'Diaye
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - E Arenholz
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - J A Mundy
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - T Venkatesan
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
- NUSNNI-Nanocore, National University of Singapore, Singapore 117411, Singapore
| | - D A Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - L-W Wang
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Jian Liu
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - L W Martin
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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43
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Eom K, Choi E, Yoon J, Choi M, Song K, Choi SY, Lee D, Lee JW, Eom CB, Lee J. Electron-Lattice Coupling in Correlated Materials of Low Electron Occupancy. NANO LETTERS 2017; 17:5458-5463. [PMID: 28850246 DOI: 10.1021/acs.nanolett.7b02109] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In correlated materials including transition metal oxides, electronic properties and functionalities are modulated and enriched by couplings between the electron and lattice degrees of freedom. These couplings are controlled by external parameters such as chemical doping, pressure, magnetic and electric fields, and light irradiation. However, the electron-lattice coupling relies on orbital characters, i.e., symmetry and occupancy, of t2g and eg orbitals, so that a large electron-lattice coupling is limited to eg electron system, whereas t2g electron system exhibits an inherently weak coupling. Here, we design and demonstrate a strongly enhanced electron-lattice coupling in electron-doped SrTiO3, that is, the t2g electron system. In ultrathin films of electron-doped SrTiO3 [i.e., (La0.25Sr0.75)TiO3], we reveal the strong electron-lattice-orbital coupling, which is manifested by extremely increased tetragonality and the corresponding metal-to-insulator transition. Our findings open the way of an active tuning of the charge-lattice-orbital coupling to obtain new functionalities relevant to emerging nanoelectronic devices.
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Affiliation(s)
- Kitae Eom
- School of Advanced Materials Science and Engineering, Sungkyunkwan University , Suwon 16419, Republic of Korea
| | - Euiyoung Choi
- School of Advanced Materials Science and Engineering, Sungkyunkwan University , Suwon 16419, Republic of Korea
| | - Jonghyun Yoon
- School of Advanced Materials Science and Engineering, Sungkyunkwan University , Suwon 16419, Republic of Korea
| | - Minsu Choi
- School of Advanced Materials Science and Engineering, Sungkyunkwan University , Suwon 16419, Republic of Korea
| | - Kyung Song
- Department of Materials Modeling and Characterization, Korea Institute of Materials Science , Changwon 51508, Republic of Korea
| | - Si-Young Choi
- Department of Materials Modeling and Characterization, Korea Institute of Materials Science , Changwon 51508, Republic of Korea
| | - Daesu Lee
- Department of Materials Science and Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53792, United States
| | - Jung-Woo Lee
- Department of Materials Science and Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53792, United States
| | - Chang-Beom Eom
- Department of Materials Science and Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53792, United States
| | - Jaichan Lee
- School of Advanced Materials Science and Engineering, Sungkyunkwan University , Suwon 16419, Republic of Korea
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44
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Abstract
The band alignment at an Al2O3/SrTiO3 heterointerface forming a two-dimensional electron gas (2DEG) was investigated using scanning photocurrent microscopy (SPCM) in an electrolyte-gated environment. We used a focused UV laser source for above-the-bandgap illumination on the SrTiO3 layer, creating electron-hole pairs that contributed to the photocurrent through migration towards the metal electrodes. The polarity of the SPCM signals of a bare SrTiO3 device shows typical p-type behavior at zero gate bias, in which the photogenerated electrons are collected by the electrodes. In contrast, the SPCM polarity of 2DEG device indicates that the hole carriers were collected by the metal electrodes. Careful transport measurements revealed that the gate-dependent conductance of the 2DEG devices exhibits n-type switching behavior. More importantly, the SPCM signals in 2DEG devices demonstrated very unique gate-responses that cannot be found in conventional semiconducting devices, based on which we were able to perform detailed investigation into the electronic band alignment of the 2DEG devices and obtain the valence band offset at the heterointerface.
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45
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Tsai MS, Li CS, Guo ST, Song MY, Singh AK, Lee WL, Chu MW. Off-Stoichiometry Driven Carrier Density Variation at the Interface of LaAlO 3/SrTiO 3. Sci Rep 2017; 7:1770. [PMID: 28496105 PMCID: PMC5431992 DOI: 10.1038/s41598-017-02039-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 04/05/2017] [Indexed: 11/28/2022] Open
Abstract
The interface between LaAlO3 (LAO) and SrTiO3 (STO) has attracted enormous interests due to its rich physical phenomena, such as metallic nature, magnetism and superconductivity. In this work, we report our experimental investigations on the influence of the LAO stoichiometry to the metallic interface. Taking advantage of the oxide molecular beam epitaxy (MBE) technique, a series of high quality LAO films with different nominal La/Al ratios and LAO thicknesses were grown on the TiO2-terminated STO substrates, where systematic variations of the LAO lattice constant and transport property were observed. In particular, the sheet density can be largely reduced by nearly an order of magnitude with merely about 20% increase in the nominal La/Al ratio. Our finding provides an effective method on tuning the electron density of the two-dimensional electron liquid (2DEL) at the LAO/STO interface.
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Affiliation(s)
- Ming-Shiu Tsai
- Institute of Physics, Academia Sinica, Nankang, Taipei, 11529, Taiwan
| | - Chi-Sheng Li
- Institute of Physics, Academia Sinica, Nankang, Taipei, 11529, Taiwan
| | - Shih-Ting Guo
- Institute of Physics, Academia Sinica, Nankang, Taipei, 11529, Taiwan
| | - Ming-Yuan Song
- Institute of Physics, Academia Sinica, Nankang, Taipei, 11529, Taiwan
| | - Akhilesh Kr Singh
- Institute of Physics, Academia Sinica, Nankang, Taipei, 11529, Taiwan.
| | - Wei-Li Lee
- Institute of Physics, Academia Sinica, Nankang, Taipei, 11529, Taiwan.
| | - M-W Chu
- Center for Condensed Matter Sciences, National Taiwan University, Taipei, 10617, Taiwan
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46
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Hellman F, Hoffmann A, Tserkovnyak Y, Beach GSD, Fullerton EE, Leighton C, MacDonald AH, Ralph DC, Arena DA, Dürr HA, Fischer P, Grollier J, Heremans JP, Jungwirth T, Kimel AV, Koopmans B, Krivorotov IN, May SJ, Petford-Long AK, Rondinelli JM, Samarth N, Schuller IK, Slavin AN, Stiles MD, Tchernyshyov O, Thiaville A, Zink BL. Interface-Induced Phenomena in Magnetism. REVIEWS OF MODERN PHYSICS 2017; 89:025006. [PMID: 28890576 PMCID: PMC5587142 DOI: 10.1103/revmodphys.89.025006] [Citation(s) in RCA: 192] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
This article reviews static and dynamic interfacial effects in magnetism, focusing on interfacially-driven magnetic effects and phenomena associated with spin-orbit coupling and intrinsic symmetry breaking at interfaces. It provides a historical background and literature survey, but focuses on recent progress, identifying the most exciting new scientific results and pointing to promising future research directions. It starts with an introduction and overview of how basic magnetic properties are affected by interfaces, then turns to a discussion of charge and spin transport through and near interfaces and how these can be used to control the properties of the magnetic layer. Important concepts include spin accumulation, spin currents, spin transfer torque, and spin pumping. An overview is provided to the current state of knowledge and existing review literature on interfacial effects such as exchange bias, exchange spring magnets, spin Hall effect, oxide heterostructures, and topological insulators. The article highlights recent discoveries of interface-induced magnetism and non-collinear spin textures, non-linear dynamics including spin torque transfer and magnetization reversal induced by interfaces, and interfacial effects in ultrafast magnetization processes.
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Affiliation(s)
- Frances Hellman
- Department of Physics, University of California, Berkeley, Berkeley, California 94720, USA; Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Axel Hoffmann
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Yaroslav Tserkovnyak
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
| | - Geoffrey S D Beach
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Eric E Fullerton
- Center for Memory and Recording Research, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0401, USA
| | - Chris Leighton
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Allan H MacDonald
- Department of Physics, University of Texas at Austin, Austin, Texas 78712-0264, USA
| | - Daniel C Ralph
- Physics Department, Cornell University, Ithaca, New York 14853, USA; Kavli Institute at Cornell, Cornell University, Ithaca, New York 14853, USA
| | - Dario A Arena
- Department of Physics, University of South Florida, Tampa, Florida 33620-7100, USA
| | - Hermann A Dürr
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - Peter Fischer
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA; Physics Department, University of California, 1156 High Street, Santa Cruz, California 94056, USA
| | - Julie Grollier
- Unité Mixte de Physique CNRS/Thales and Université Paris Sud 11, 1 Avenue Fresnel, 91767 Palaiseau, France
| | - Joseph P Heremans
- Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, Ohio 43210, USA; Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210, USA; Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Tomas Jungwirth
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 162 53 Praha 6, Czech Republic; School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Alexey V Kimel
- Radboud University, Institute for Molecules and Materials, Nijmegen 6525 AJ, The Netherlands
| | - Bert Koopmans
- Department of Applied Physics, Center for NanoMaterials, COBRA Research Institute, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Ilya N Krivorotov
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
| | - Steven J May
- Department of Materials Science & Engineering, Drexel University, Philadelphia, Pennsylvania 19104, USA
| | - Amanda K Petford-Long
- Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA; Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, USA
| | - James M Rondinelli
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA
| | - Nitin Samarth
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Ivan K Schuller
- Department of Physics and Center for Advanced Nanoscience, University of California, San Diego, La Jolla, California 92093, USA; Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093, USA
| | - Andrei N Slavin
- Department of Physics, Oakland University, Rochester, Michigan 48309, USA
| | - Mark D Stiles
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6202, USA
| | - Oleg Tchernyshyov
- Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - André Thiaville
- Laboratoire de Physique des Solides, UMR CNRS 8502, Université Paris-Sud, 91405 Orsay, France
| | - Barry L Zink
- Department of Physics and Astronomy, University of Denver, Denver, CO 80208, USA
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47
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Smink AEM, de Boer JC, Stehno MP, Brinkman A, van der Wiel WG, Hilgenkamp H. Gate-Tunable Band Structure of the LaAlO_{3}-SrTiO_{3} Interface. PHYSICAL REVIEW LETTERS 2017; 118:106401. [PMID: 28339281 DOI: 10.1103/physrevlett.118.106401] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Indexed: 06/06/2023]
Abstract
The two-dimensional electron system at the interface between LaAlO_{3} and SrTiO_{3} has several unique properties that can be tuned by an externally applied gate voltage. In this work, we show that this gate tunability extends to the effective band structure of the system. We combine a magnetotransport study on top-gated Hall bars with self-consistent Schrödinger-Poisson calculations and observe a Lifshitz transition at a density of 2.9×10^{13}cm^{-2}. Above the transition, the carrier density of one of the conducting bands decreases with increasing gate voltage. This surprising decrease is accurately reproduced in the calculations if electronic correlations are included. These results provide a clear, intuitive picture of the physics governing the electronic structure at complex-oxide interfaces.
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Affiliation(s)
- A E M Smink
- MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - J C de Boer
- MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - M P Stehno
- MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - A Brinkman
- MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - W G van der Wiel
- MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - H Hilgenkamp
- MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
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48
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Zhang J, Zhang H, Zhang X, Guan X, Shen X, Hong D, Zhang H, Liu B, Yu R, Shen B, Sun J. Antiferromagnetic interlayer coupling and thus induced distinct spin texture for the [LaMnO 3/LaCoO 3] 5 superlattices. NANOSCALE 2017; 9:3476-3484. [PMID: 28239702 DOI: 10.1039/c6nr09242j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Artificial engineering of an interfacial spin structure of complex oxides with strongly coupled spin, orbital, charge and lattice degrees of freedom is crucially important for the exploration of novel effects associated with magnetic tunneling, exchange biasing, and spin injecting/manipulating, which are the central issues of spintronics. Here we demonstrate the presence of a distinct interlayer coupling between LaMnO3 (LMO) and LaCoO3 (LCO) and the resulting dramatic effect on the spin structure. We found that the LCO layer in (LMO/LCO)5 superlattices exhibits not only an antiferromagnetic coupling with a neighboring LMO layer but also a long-range magnetic order with substantially reduced magnetization. As suggested by density functional theory calculations, interlayer coupling can induce a spatial oscillation of magnetic moment within the LCO layer, resulting in low magnetization.
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Affiliation(s)
- Jing Zhang
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
| | - Hongrui Zhang
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
| | - Xuejing Zhang
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
| | - Xiangxiang Guan
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
| | - Xi Shen
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
| | - Deshun Hong
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
| | - Hui Zhang
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
| | - Banggui Liu
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
| | - Richeng Yu
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
| | - Baogen Shen
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
| | - Jirong Sun
- Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
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49
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Liang Y, Vinson J, Pemmaraju S, Drisdell WS, Shirley EL, Prendergast D. Accurate X-Ray Spectral Predictions: An Advanced Self-Consistent-Field Approach Inspired by Many-Body Perturbation Theory. PHYSICAL REVIEW LETTERS 2017; 118:096402. [PMID: 28306298 PMCID: PMC5532736 DOI: 10.1103/physrevlett.118.096402] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Indexed: 05/06/2023]
Abstract
Constrained-occupancy delta-self-consistent-field (ΔSCF) methods and many-body perturbation theories (MBPT) are two strategies for obtaining electronic excitations from first principles. Using the two distinct approaches, we study the O 1s core excitations that have become increasingly important for characterizing transition-metal oxides and understanding strong electronic correlation. The ΔSCF approach, in its current single-particle form, systematically underestimates the pre-edge intensity for chosen oxides, despite its success in weakly correlated systems. By contrast, the Bethe-Salpeter equation within MBPT predicts much better line shapes. This motivates one to reexamine the many-electron dynamics of x-ray excitations. We find that the single-particle ΔSCF approach can be rectified by explicitly calculating many-electron transition amplitudes, producing x-ray spectra in excellent agreement with experiments. This study paves the way to accurately predict x-ray near-edge spectral fingerprints for physics and materials science beyond the Bethe-Salpether equation.
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Affiliation(s)
- Yufeng Liang
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - John Vinson
- National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, USA
| | - Sri Pemmaraju
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Walter S Drisdell
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Eric L Shirley
- National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, USA
| | - David Prendergast
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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50
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Wang F, Ren Z, Tian H, Yang SA, Xie Y, Lu Y, Jiang J, Han G, Yang K. Interfacial Multiferroics of TiO 2/PbTiO 3 Heterostructure Driven by Ferroelectric Polarization Discontinuity. ACS APPLIED MATERIALS & INTERFACES 2017; 9:1899-1906. [PMID: 27990804 DOI: 10.1021/acsami.6b13183] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Novel phenomena appear when two different oxide materials are combined together to form an interface. For example, at the interface of LaAlO3/SrTiO3, two-dimensional conductive states form to avoid the polar discontinuity, and magnetic properties are found at such an interface. In this work, we propose a new type of interface between two nonmagnetic and nonpolar oxides that could host a magnetic state, where it is the ferroelectric polarization discontinuity instead of the polar discontinuity that leads to the charge transfer, forming the interfacial magnetic state. As a concrete example, we investigate by first-principles calculations the heterostructures made of ferroelectric perovskite oxide PbTiO3 and nonferroelectric polarized oxide TiO2. We show that charge is transferred to the interfacial layer forming an interfacial ferromagnetic ordering that may persist up to room temperature. Especially, the strong coupling between bulk ferroelectric polarization and interface ferromagnetism represents a new type of magnetoelectric effect, which provides an ideal platform for exploring the intriguing interfacial multiferroics. The findings here are important not only for fundamental science but also for promising applications in nanoscale electronics and spintronics.
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Affiliation(s)
| | | | | | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design , Singapore 487372, Singapore
| | | | | | | | | | - Kesong Yang
- Department of NanoEngineering, University of California , San Diego, 9500 Gilman Drive, Mail Code 0448, La Jolla, California 92093-0448, United States
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