51
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Groenendijk DJ, Autieri C, Girovsky J, Martinez-Velarte MC, Manca N, Mattoni G, Monteiro AMRVL, Gauquelin N, Verbeeck J, Otte AF, Gabay M, Picozzi S, Caviglia AD. Spin-Orbit Semimetal SrIrO_{3} in the Two-Dimensional Limit. PHYSICAL REVIEW LETTERS 2017; 119:256403. [PMID: 29303305 DOI: 10.1103/physrevlett.119.256403] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Indexed: 06/07/2023]
Abstract
We investigate the thickness-dependent electronic properties of ultrathin SrIrO_{3} and discover a transition from a semimetallic to a correlated insulating state below 4 unit cells. Low-temperature magnetoconductance measurements show that spin fluctuations in the semimetallic state are significantly enhanced while approaching the transition point. The electronic properties are further studied by scanning tunneling spectroscopy, showing that 4 unit cell SrIrO_{3} is on the verge of a gap opening. Our density functional theory calculations reproduce the critical thickness of the transition and show that the opening of a gap in ultrathin SrIrO_{3} requires antiferromagnetic order.
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Affiliation(s)
- D J Groenendijk
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, Netherlands
| | - C Autieri
- Consiglio Nazionale delle Ricerche CNR-SPIN, UOS L'Aquila, Sede Temporanea di Chieti, 66100 Chieti, Italy
| | - J Girovsky
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, Netherlands
| | - M Carmen Martinez-Velarte
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, Netherlands
| | - N Manca
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, Netherlands
| | - G Mattoni
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, Netherlands
| | - A M R V L Monteiro
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, Netherlands
| | - N Gauquelin
- Electron Microscopy for Materials Science (EMAT), University of Antwerp, 2020 Antwerp, Belgium
| | - J Verbeeck
- Electron Microscopy for Materials Science (EMAT), University of Antwerp, 2020 Antwerp, Belgium
| | - A F Otte
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, Netherlands
| | - M Gabay
- Laboratoire de Physique des Solides, Bat 510, Université Paris-Sud, 91405 Orsay, France
| | - S Picozzi
- Consiglio Nazionale delle Ricerche CNR-SPIN, UOS L'Aquila, Sede Temporanea di Chieti, 66100 Chieti, Italy
| | - A D Caviglia
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, Netherlands
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52
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Kobayashi M, Yoshimatsu K, Mitsuhashi T, Kitamura M, Sakai E, Yukawa R, Minohara M, Fujimori A, Horiba K, Kumigashira H. Emergence of Quantum Critical Behavior in Metallic Quantum-Well States of Strongly Correlated Oxides. Sci Rep 2017; 7:16621. [PMID: 29192172 PMCID: PMC5709408 DOI: 10.1038/s41598-017-16666-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 10/05/2017] [Indexed: 11/09/2022] Open
Abstract
Controlling quantum critical phenomena in strongly correlated electron systems, which emerge in the neighborhood of a quantum phase transition, is a major challenge in modern condensed matter physics. Quantum critical phenomena are generated from the delicate balance between long-range order and its quantum fluctuation. So far, the nature of quantum phase transitions has been investigated by changing a limited number of external parameters such as pressure and magnetic field. We propose a new approach for investigating quantum criticality by changing the strength of quantum fluctuation that is controlled by the dimensional crossover in metallic quantum well (QW) structures of strongly correlated oxides. With reducing layer thickness to the critical thickness of metal-insulator transition, crossover from a Fermi liquid to a non-Fermi liquid has clearly been observed in the metallic QW of SrVO3 by in situ angle-resolved photoemission spectroscopy. Non-Fermi liquid behavior with the critical exponent α = 1 is found to emerge in the two-dimensional limit of the metallic QW states, indicating that a quantum critical point exists in the neighborhood of the thickness-dependent Mott transition. These results suggest that artificial QW structures provide a unique platform for investigating novel quantum phenomena in strongly correlated oxides in a controllable fashion.
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Affiliation(s)
- Masaki Kobayashi
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, 305-0801, Japan.
| | - Kohei Yoshimatsu
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, 305-0801, Japan.,Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Taichi Mitsuhashi
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, 305-0801, Japan.,Department of Physics, Tohoku University, Sendai, 980-8577, Japan
| | - Miho Kitamura
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, 305-0801, Japan
| | - Enju Sakai
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, 305-0801, Japan
| | - Ryu Yukawa
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, 305-0801, Japan
| | - Makoto Minohara
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, 305-0801, Japan
| | - Atsushi Fujimori
- Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Koji Horiba
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, 305-0801, Japan
| | - Hiroshi Kumigashira
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, 305-0801, Japan. .,Department of Physics, Tohoku University, Sendai, 980-8577, Japan.
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53
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Zhou G, Yan Z, Bai Y, Zang J, Quan Z, Qi S, Xu X. Exchange Bias Effect and Orbital Reconstruction in (001)-Oriented LaMnO 3/LaNiO 3 Superlattices. ACS APPLIED MATERIALS & INTERFACES 2017; 9:39855-39862. [PMID: 29057645 DOI: 10.1021/acsami.7b14503] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Paramagnetic LaNiO3 (LNO)-based heterostructures have been attracting the attention of researches, especially since the interesting exchange bias (EB) effect has been observed in (111)-oriented LaMnO3 (LMO)/LNO superlattices (SLs). However, this effect is not expected to occur in the (001) direction SLs. In this paper, we report the observation of an unexpected EB effect in (001)-oriented (LMO)3/(LNO)t SLs. The orbits of interfacial Mn/Ni ions preferentially occupy the strain-stabilized x2 - y2 in ultrathin LNO layers [t ≤ 4 unit cells (u.c.)]. Conversely, as the LNO layer becomes thicker (t ≥ 6 u.c.), the EB effect is absent, and the orbits are reconstructed to form the 3z2 - r2 preferential occupancy. The absence of the EB in thicker LNO-based SLs is attributed to the interfacial charge transfer suppressed by orbital reconstruction as a consequence of the increasing LNO thickness. In the thinner LNO-based SLs, the larger charge transfer results in stronger localized magnetic moments for the cause of the EB effect. These results provide a useful interpretation of the relationship between macroscopic magnetic properties and the microscopic electronic structure in oxide-based heterostructures.
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Affiliation(s)
- Guowei Zhou
- School of Chemistry and Materials Science of Shanxi Normal University & Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education , Linfen 041004, China
- Research Institute of Materials Science of Shanxi Normal University & Collaborative Innovation Center for Shanxi Advanced Permanent Magnetic Materials and Techonology , Linfen 041004, China
| | - Zhi Yan
- School of Chemistry and Materials Science of Shanxi Normal University & Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education , Linfen 041004, China
| | - Yuhao Bai
- Research Institute of Materials Science of Shanxi Normal University & Collaborative Innovation Center for Shanxi Advanced Permanent Magnetic Materials and Techonology , Linfen 041004, China
| | - Julu Zang
- School of Chemistry and Materials Science of Shanxi Normal University & Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education , Linfen 041004, China
| | - Zhiyong Quan
- School of Chemistry and Materials Science of Shanxi Normal University & Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education , Linfen 041004, China
- Research Institute of Materials Science of Shanxi Normal University & Collaborative Innovation Center for Shanxi Advanced Permanent Magnetic Materials and Techonology , Linfen 041004, China
| | - Shifei Qi
- School of Chemistry and Materials Science of Shanxi Normal University & Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education , Linfen 041004, China
- Research Institute of Materials Science of Shanxi Normal University & Collaborative Innovation Center for Shanxi Advanced Permanent Magnetic Materials and Techonology , Linfen 041004, China
| | - Xiaohong Xu
- School of Chemistry and Materials Science of Shanxi Normal University & Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education , Linfen 041004, China
- Research Institute of Materials Science of Shanxi Normal University & Collaborative Innovation Center for Shanxi Advanced Permanent Magnetic Materials and Techonology , Linfen 041004, China
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54
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Bak J, Bae HB, Kim J, Oh J, Chung SY. Formation of Two-Dimensional Homologous Faults and Oxygen Electrocatalytic Activities in a Perovskite Nickelate. NANO LETTERS 2017; 17:3126-3132. [PMID: 28394129 DOI: 10.1021/acs.nanolett.7b00561] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Atomic-scale direct probing of active sites and subsequent elucidation of the structure-activity relationship are important issues involving oxide-based electrocatalysts to achieve better electrochemical conversion efficiency. By generating Ruddlesden-Popper (RP) two-dimensional homologous faults via simple control of the cation nonstoichiometry in LaNiO3 thin films, we demonstrate that strong tetragonal distortion of [NiO6] octahedra is induced by more than 20% elongation of Ni-O bonds in the faults. In addition to direct visualization of the elongation by scanning transmission electron microscopy, we identify that the distorted [NiO6] octahedra in the faults show considerably higher electrocatalytic activities than other surface sites during the electrochemical oxygen evolution reaction. This unequivocal evidence of the octahedral distortion and its impact on electrocatalysis in LaNiO3 suggests that the formation of RP-type faults can provide an efficient way to control the octahedral geometry and thereby remarkably enhance the oxygen catalytic performance of perovskite oxides.
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Affiliation(s)
- Jumi Bak
- Graduate School of EEWS and ‡KAIST Analysis Center, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea
| | - Hyung Bin Bae
- Graduate School of EEWS and ‡KAIST Analysis Center, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea
| | - Jaehoon Kim
- Graduate School of EEWS and ‡KAIST Analysis Center, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea
| | - Jihun Oh
- Graduate School of EEWS and ‡KAIST Analysis Center, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea
| | - Sung-Yoon Chung
- Graduate School of EEWS and ‡KAIST Analysis Center, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea
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55
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Fowlie J, Gibert M, Tieri G, Gloter A, Íñiguez J, Filippetti A, Catalano S, Gariglio S, Schober A, Guennou M, Kreisel J, Stéphan O, Triscone JM. Conductivity and Local Structure of LaNiO 3 Thin Films. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1605197. [PMID: 28262988 DOI: 10.1002/adma.201605197] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 01/10/2017] [Indexed: 06/06/2023]
Abstract
A marked conductivity enhancement is reported in 6-11 unit cell LaNiO3 thin films. A maximal conductivity is also observed in ab initio calculations for films of the same thickness. In agreement with results from state of the art scanning transmission electron microscopy, the calculations also reveal a differentiated film structure comprising characteristic surface, interior, and heterointerface structures. Based on this observation, a three-element parallel conductor model is considered and leads to the conclusion that the conductivity enhancement for films of 6-11 unit cells, stems from the onset of intercompetition between the three local structures in the film depth.
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Affiliation(s)
- Jennifer Fowlie
- DQMP, Université de Genève, 24 Quai E.-Ansermet, 1211, Geneva, Switzerland
| | - Marta Gibert
- DQMP, Université de Genève, 24 Quai E.-Ansermet, 1211, Geneva, Switzerland
| | - Giulio Tieri
- DQMP, Université de Genève, 24 Quai E.-Ansermet, 1211, Geneva, Switzerland
- Laboratoire de Physique des Solides, CNRS UMR8502, Université Paris-Sud, 91405, Orsay, France
| | - Alexandre Gloter
- Laboratoire de Physique des Solides, CNRS UMR8502, Université Paris-Sud, 91405, Orsay, France
| | - Jorge Íñiguez
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology, 41 Rue du Brill, 4422, Belvaux, Luxembourg
| | - Alessio Filippetti
- Istituto dei Materiali, CNR-IOM and Dipartimento di Fisica, Università di Cagliari, Monserrato, 09042-I, Cagliari, Italy
| | - Sara Catalano
- DQMP, Université de Genève, 24 Quai E.-Ansermet, 1211, Geneva, Switzerland
| | - Stefano Gariglio
- DQMP, Université de Genève, 24 Quai E.-Ansermet, 1211, Geneva, Switzerland
| | - Alexander Schober
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology, 41 Rue du Brill, 4422, Belvaux, Luxembourg
| | - Mael Guennou
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology, 41 Rue du Brill, 4422, Belvaux, Luxembourg
| | - Jens Kreisel
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology, 41 Rue du Brill, 4422, Belvaux, Luxembourg
- Physics and Materials Science Research Unit, University of Luxembourg, 41 Rue du Brill, 4422, Belvaux, Luxembourg
| | - Odile Stéphan
- Laboratoire de Physique des Solides, CNRS UMR8502, Université Paris-Sud, 91405, Orsay, France
| | - Jean-Marc Triscone
- DQMP, Université de Genève, 24 Quai E.-Ansermet, 1211, Geneva, Switzerland
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56
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Zhou G, Song C, Bai Y, Quan Z, Jiang F, Liu W, Xu Y, Dhesi SS, Xu X. Robust Interfacial Exchange Bias and Metal-Insulator Transition Influenced by the LaNiO 3 Layer Thickness in La 0.7Sr 0.3MnO 3/LaNiO 3 Superlattices. ACS APPLIED MATERIALS & INTERFACES 2017; 9:3156-3160. [PMID: 28067035 DOI: 10.1021/acsami.6b14372] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Artificial heterostructures based on LaNiO3 (LNO) have been widely investigated with the aim to realize the insulating antiferromagnetic state of LNO. In this work, we grew [(La0.7Sr0.3MnO3)5-(LaNiO3)n]12 superlattices on (001)-oriented SrTiO3 substrates by pulsed laser deposition and observed an unexpected exchange bias effect in field-cooled hysteresis loops. Through X-ray absorption spectroscopy and magnetic circular dichroism experiments, we found that the charge transfer at the interfacial Mn and Ni ions can induce a localized magnetic moment. A remarkable increase of exchange bias field and a transition from metal to insulator were simultaneously observed upon decreasing the thickness of the LNO layer, indicating the antiferromagnetic insulator state in 2 unit cells LNO ultrathin layers. The robust exchange bias of 745 Oe in the superlattice is caused by an interfacial localized magnetic moment and an antiferromagnetic state in the ultrathin LNO layer, pinning the ferromagnetic La0.7Sr0.3MnO3 layers together. Our results demonstrate that artificial interface engineering is a useful method to realize novel magnetic and transport properties.
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Affiliation(s)
- Guowei Zhou
- School of Chemistry and Materials Science, Key Laboratory of Magnetic Molecules and Magnetic Information Materials, Ministry of Education, Shanxi Normal University , Linfen 041004, China
- Research Institute of Materials Science, Shanxi Normal University , Linfen 041004, China
| | - Cheng Song
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University , Beijing 100084, China
| | - Yuhao Bai
- School of Chemistry and Materials Science, Key Laboratory of Magnetic Molecules and Magnetic Information Materials, Ministry of Education, Shanxi Normal University , Linfen 041004, China
- Research Institute of Materials Science, Shanxi Normal University , Linfen 041004, China
| | - Zhiyong Quan
- School of Chemistry and Materials Science, Key Laboratory of Magnetic Molecules and Magnetic Information Materials, Ministry of Education, Shanxi Normal University , Linfen 041004, China
- Research Institute of Materials Science, Shanxi Normal University , Linfen 041004, China
| | - Fengxian Jiang
- School of Chemistry and Materials Science, Key Laboratory of Magnetic Molecules and Magnetic Information Materials, Ministry of Education, Shanxi Normal University , Linfen 041004, China
- Research Institute of Materials Science, Shanxi Normal University , Linfen 041004, China
| | - Wenqing Liu
- Spintronics and Nanodevice Laboratory, Department of Electronics, University of York , York YO10 5DD, U.K
- Department of Electronic Engineering, Royal Holloway, University of London , Egham, Surrey TW20 0EX, U.K
| | - Yongbing Xu
- Spintronics and Nanodevice Laboratory, Department of Electronics, University of York , York YO10 5DD, U.K
| | - Sarnjeet S Dhesi
- Harwell Science and Innovation Campus, Diamond Light Source , Didcot, Oxfordshire OX11 0DE, U.K
| | - Xiaohong Xu
- School of Chemistry and Materials Science, Key Laboratory of Magnetic Molecules and Magnetic Information Materials, Ministry of Education, Shanxi Normal University , Linfen 041004, China
- Research Institute of Materials Science, Shanxi Normal University , Linfen 041004, China
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57
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Wang L, Chang L, Yin X, Rusydi A, You L, Zhou Y, Fang L, Wang J. Localization-driven metal-insulator transition in epitaxial hole-doped Nd 1-x Sr x NiO 3 ultrathin films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:025002. [PMID: 27845934 DOI: 10.1088/0953-8984/29/2/025002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Advances in thin film growth technologies make it possible to obtain ultra-thin perovskite oxide films and open the window for controlling novel electronic phases for use in functional nanoscale electronics, such as switches and sensors. Here, we study the thickness-dependent transport characteristics of high-quality ultrathin Nd0.9Sr0.1NiO3 (Sr-NNO) films, which were grown on LaAlO3 (0 0 1) single-crystal substrates by using pulsed laser deposition method. Thick Sr-NNO films (25 unit cells) exhibit metallic behavior with the electrical resistivity following the T n (n < 2) law corresponding to a non-Fermi liquid system, while a temperature driven metal-insulator transition (MIT) is observed with films of less than 15 unit cells. The transition temperature increases with reducing film thickness, until the insulating characteristic is observed even at room temperature. The emergence of the insulator ground state can be attributed to weak localization driven MIT expected by considering Mott-Ioffe-Regel limit. Furthermore, the magneto-transport study of Sr-NNO ultrathin films also confirms that the observed MIT is due to the disorder-induced localization rather than the electron-electron interactions.
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Affiliation(s)
- Le Wang
- School of Material Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
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58
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Atomic-scale control of magnetic anisotropy via novel spin-orbit coupling effect in La2/3Sr1/3MnO3/SrIrO3 superlattices. Proc Natl Acad Sci U S A 2016; 113:6397-402. [PMID: 27199482 DOI: 10.1073/pnas.1524689113] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Magnetic anisotropy (MA) is one of the most important material properties for modern spintronic devices. Conventional manipulation of the intrinsic MA, i.e., magnetocrystalline anisotropy (MCA), typically depends upon crystal symmetry. Extrinsic control over the MA is usually achieved by introducing shape anisotropy or exchange bias from another magnetically ordered material. Here we demonstrate a pathway to manipulate MA of 3d transition-metal oxides (TMOs) by digitally inserting nonmagnetic 5d TMOs with pronounced spin-orbit coupling (SOC). High-quality superlattices comprising ferromagnetic La2/3Sr1/3MnO3 (LSMO) and paramagnetic SrIrO3 (SIO) are synthesized with the precise control of thickness at the atomic scale. Magnetic easy-axis reorientation is observed by controlling the dimensionality of SIO, mediated through the emergence of a novel spin-orbit state within the nominally paramagnetic SIO.
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59
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Kim TH, Puggioni D, Yuan Y, Xie L, Zhou H, Campbell N, Ryan PJ, Choi Y, Kim JW, Patzner JR, Ryu S, Podkaminer JP, Irwin J, Ma Y, Fennie CJ, Rzchowski MS, Pan XQ, Gopalan V, Rondinelli JM, Eom CB. Polar metals by geometric design. Nature 2016; 533:68-72. [DOI: 10.1038/nature17628] [Citation(s) in RCA: 215] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 02/22/2016] [Indexed: 11/09/2022]
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60
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Liao Z, Huijben M, Zhong Z, Gauquelin N, Macke S, Green RJ, Van Aert S, Verbeeck J, Van Tendeloo G, Held K, Sawatzky GA, Koster G, Rijnders G. Controlled lateral anisotropy in correlated manganite heterostructures by interface-engineered oxygen octahedral coupling. NATURE MATERIALS 2016; 15:425-31. [PMID: 26950593 DOI: 10.1038/nmat4579] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 01/22/2016] [Indexed: 05/27/2023]
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61
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Engineered Mott ground state in a LaTiO(3+δ)/LaNiO3 heterostructure. Nat Commun 2016; 7:10418. [PMID: 26791402 PMCID: PMC4735946 DOI: 10.1038/ncomms10418] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 12/09/2015] [Indexed: 11/08/2022] Open
Abstract
In pursuit of creating cuprate-like electronic and orbital structures, artificial heterostructures based on LaNiO3 have inspired a wealth of exciting experimental and theoretical results. However, to date there is a very limited experimental understanding of the electronic and orbital states emerging from interfacial charge transfer and their connections to the modified band structure at the interface. Towards this goal, we have synthesized a prototypical superlattice composed of a correlated metal LaNiO3 and a doped Mott insulator LaTiO3+δ, and investigated its electronic structure by resonant X-ray absorption spectroscopy combined with X-ray photoemission spectroscopy, electrical transport and theory calculations. The heterostructure exhibits interfacial charge transfer from Ti to Ni sites, giving rise to an insulating ground state with orbital polarization and eg orbital band splitting. Our findings demonstrate how the control over charge at the interface can be effectively used to create exotic electronic, orbital and spin states. Interfaces between two dissimilar transition metal oxides can exhibit emergent strongly correlated electronic and magnetic states due to charge transfer and electronic reconfiguration. Here, the authors synthesize and investigate an exotic Mott ground state in LaTiO3+δ/LaNiO3 heterostructures.
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62
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Wang L, Ju S, You L, Qi Y, Guo YW, Ren P, Zhou Y, Wang J. Competition between strain and dimensionality effects on the electronic phase transitions in NdNiO3 films. Sci Rep 2015; 5:18707. [PMID: 26687924 PMCID: PMC4685315 DOI: 10.1038/srep18707] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 11/23/2015] [Indexed: 11/08/2022] Open
Abstract
Transition metal oxides host an array of exotic electronic phases, including superconductivity, ferroelectricity, quantum spin liquid and Mott insulators. Their extreme sensitivity to external stimuli enables various routes to manipulate the ground state, which greatly improves our understanding of the physics involved. Here, we report the competition between strain and dimensionality effects on the phase evolution in high quality NdNiO3 films down to several unit cells. While both compressive and tensile strains increase the Ni 3d band width and favor the metallic phase, reducing dimensionality, on the other hand, decreases the covalent band width and favors the insulating phase in NdNiO3. The experimental observations are well supported by ab initio calculations and improve our understanding of the electronic behavior in strongly correlated electron systems.
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Affiliation(s)
- Le Wang
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Sheng Ju
- School of Physical Science and Technology, Soochow University, Suzhou 215006, China
| | - Lu You
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Yajun Qi
- School of Materials Science and Engineering, Hubei University, Wuhan 430062, China
| | - Yu-wei Guo
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Peng Ren
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Yang Zhou
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Junling Wang
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
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63
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Mikheev E, Hauser AJ, Himmetoglu B, Moreno NE, Janotti A, Van de Walle CG, Stemmer S. Tuning bad metal and non-Fermi liquid behavior in a Mott material: Rare-earth nickelate thin films. SCIENCE ADVANCES 2015; 1:e1500797. [PMID: 26601140 PMCID: PMC4640588 DOI: 10.1126/sciadv.1500797] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 08/28/2015] [Indexed: 05/05/2023]
Abstract
Resistances that exceed the Mott-Ioffe-Regel limit (known as bad metal behavior) and non-Fermi liquid behavior are ubiquitous features of the normal state of many strongly correlated materials. We establish the conditions that lead to bad metal and non-Fermi liquid phases in NdNiO3, which exhibits a prototype bandwidth-controlled metal-insulator transition. We show that resistance saturation is determined by the magnitude of Ni eg orbital splitting, which can be tuned by strain in epitaxial films, causing the appearance of bad metal behavior under certain conditions. The results shed light on the nature of a crossover to a non-Fermi liquid metal phase and provide a predictive criterion for Anderson localization. They elucidate a seemingly complex phase behavior as a function of film strain and confinement and provide guidelines for orbital engineering and novel devices.
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Qiao L, Jang JH, Singh DJ, Gai Z, Xiao H, Mehta A, Vasudevan RK, Tselev A, Feng Z, Zhou H, Li S, Prellier W, Zu X, Liu Z, Borisevich A, Baddorf AP, Biegalski MD. Dimensionality Controlled Octahedral Symmetry-Mismatch and Functionalities in Epitaxial LaCoO₃/SrTiO₃ Heterostructures. NANO LETTERS 2015; 15:4677-84. [PMID: 26103204 DOI: 10.1021/acs.nanolett.5b01471] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Epitaxial strain provides a powerful approach to manipulate physical properties of materials through rigid compression or extension of their chemical bonds via lattice-mismatch. Although symmetry-mismatch can lead to new physics by stabilizing novel interfacial structures, challenges in obtaining atomic-level structural information as well as lack of a suitable approach to separate it from the parasitical lattice-mismatch have limited the development of this field. Here, we present unambiguous experimental evidence that the symmetry-mismatch can be strongly controlled by dimensionality and significantly impact the collective electronic and magnetic functionalities in ultrathin perovskite LaCoO3/SrTiO3 heterojunctions. State-of-art diffraction and microscopy reveal that symmetry breaking dramatically modifies the interfacial structure of CoO6 octahedral building-blocks, resulting in expanded octahedron volume, reduced covalent screening, and stronger electron correlations. Such phenomena fundamentally alter the electronic and magnetic behaviors of LaCoO3 thin-films. We conclude that for epitaxial systems, correlation strength can be tuned by changing orbital hybridization, thus affecting the Coulomb repulsion, U, instead of by changing the band structure as the common paradigm in bulks. These results clarify the origin of magnetic ordering for epitaxial LaCoO3 and provide a route to manipulate electron correlation and magnetic functionality by orbital engineering at oxide heterojunctions.
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Affiliation(s)
- Liang Qiao
- †School of Materials, The University of Manchester, Manchester, M13 9PL, United Kingdom
| | | | | | | | | | - Apurva Mehta
- ⊥Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
| | | | | | | | | | - Sean Li
- ○School of Materials Science and Engineering, University of New South Wales, Sydney, 2052, NSW Australia
| | - Wilfrid Prellier
- ◆Laboratoire CRISMAT, CNRS UMR 6508, ENSICAEN, Normandie Université, 6 Bd Maréchal Juin, F-14050 Caen Cedex 4, France
| | | | - Zijiang Liu
- ¶Department of Physics, Lanzhou City University, Lanzhou 730070, China
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Latent instabilities in metallic LaNiO3 films by strain control of Fermi-surface topology. Sci Rep 2015; 5:8746. [PMID: 25735658 PMCID: PMC4348653 DOI: 10.1038/srep08746] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 02/02/2015] [Indexed: 11/08/2022] Open
Abstract
Strain control is one of the most promising avenues to search for new emergent phenomena in transition-metal-oxide films. Here, we investigate the strain-induced changes of electronic structures in strongly correlated LaNiO3 (LNO) films, using angle-resolved photoemission spectroscopy and the dynamical mean-field theory. The strongly renormalized eg-orbital bands are systematically rearranged by misfit strain to change its fermiology. As tensile strain increases, the hole pocket centered at the A point elongates along the kz-axis and seems to become open, thus changing Fermi-surface (FS) topology from three- to quasi-two-dimensional. Concomitantly, the FS shape becomes flattened to enhance FS nesting. A FS superstructure with Q1 = (1/2,1/2,1/2) appears in all LNO films, while a tensile-strained LNO film has an additional Q2 = (1/4,1/4,1/4) modulation, indicating that some instabilities are present in metallic LNO films. Charge disproportionation and spin-density-wave fluctuations observed in other nickelates might be their most probable origins.
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Gabay M, Triscone JM. Transition-metal oxides: It takes two to waver. NATURE NANOTECHNOLOGY 2014; 9:417-418. [PMID: 24894478 DOI: 10.1038/nnano.2014.108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Affiliation(s)
- Marc Gabay
- Laboratoire de Physique des Solides of the Université Paris-Sud, 91405 Orsay Cedex, France
| | - Jean-Marc Triscone
- Department of Condensed Matter Physics, University of Geneva, 1211 Geneva 4, Switzerland
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