1
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Fechner M, Först M, Orenstein G, Krapivin V, Disa AS, Buzzi M, von Hoegen A, de la Pena G, Nguyen QL, Mankowsky R, Sander M, Lemke H, Deng Y, Trigo M, Cavalleri A. Quenched lattice fluctuations in optically driven SrTiO 3. NATURE MATERIALS 2024; 23:363-368. [PMID: 38302742 PMCID: PMC10917662 DOI: 10.1038/s41563-023-01791-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 12/14/2023] [Indexed: 02/03/2024]
Abstract
Crystal lattice fluctuations, which are known to influence phase transitions of quantum materials in equilibrium, are also expected to determine the dynamics of light-induced phase changes. However, they have only rarely been explored in these dynamical settings. Here we study the time evolution of lattice fluctuations in the quantum paraelectric SrTiO3, in which mid-infrared drives have been shown to induce a metastable ferroelectric state. Crucial in these physics is the competition between polar instabilities and antiferrodistortive rotations, which in equilibrium frustrate the formation of long-range ferroelectricity. We make use of high-intensity mid-infrared optical pulses to resonantly drive the Ti-O-stretching mode at 17 THz, and we measure the resulting change in lattice fluctuations using time-resolved X-ray diffuse scattering at a free-electron laser. After a prompt increase, we observe a long-lived quench in R-point antiferrodistortive lattice fluctuations. Their enhancement and reduction are theoretically explained by considering the fourth-order nonlinear phononic interactions to the driven optical phonon and third-order coupling to lattice strain, respectively. These observations provide a number of testable hypotheses for the physics of light-induced ferroelectricity.
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Affiliation(s)
- M Fechner
- Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany.
| | - M Först
- Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany.
| | - G Orenstein
- Stanford Pulse Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - V Krapivin
- Stanford Pulse Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - A S Disa
- Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany
- School of Applied & Engineering Physics, Cornell University, Ithaca, NY, USA
| | - M Buzzi
- Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany
| | - A von Hoegen
- Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany
| | - G de la Pena
- Stanford Pulse Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Q L Nguyen
- Stanford Pulse Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - R Mankowsky
- Paul Scherrer Institut, Villigen, Switzerland
| | - M Sander
- Paul Scherrer Institut, Villigen, Switzerland
| | - H Lemke
- Paul Scherrer Institut, Villigen, Switzerland
| | - Y Deng
- Paul Scherrer Institut, Villigen, Switzerland
| | - M Trigo
- Stanford Pulse Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - A Cavalleri
- Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany.
- Department of Physics, Clarendon Laboratory, University of Oxford, Oxford, UK.
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2
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Kim DS, Xu M, LeBeau JM. Modeling Temperature-Dependent Electron Thermal Diffuse Scattering via Machine-Learned Interatomic Potentials and Path-Integral Molecular Dynamics. PHYSICAL REVIEW LETTERS 2024; 132:086301. [PMID: 38457736 DOI: 10.1103/physrevlett.132.086301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 01/12/2024] [Accepted: 01/25/2024] [Indexed: 03/10/2024]
Abstract
Electron thermal diffuse scattering is shown to be sensitive to subtle changes in atomic vibrations and shows promise in assessing lattice dynamics at nanometer resolution. Here, we demonstrate that machine-learned interatomic potentials (MLIPs) and path-integral molecular dynamics can accurately capture the potential energy landscape and lattice dynamics needed to describe electron thermal diffuse scattering. Using SrTiO_{3} as a test bed at cryogenic and room temperatures, we compare electron thermal diffuse scattering simulations using different approximations to incorporate thermal motion. Only when the simulations are based on quantum mechanically accurate MLIPs in combination with path-integral molecular dynamics that include nuclear quantum effects is there excellent agreement with experiments.
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Affiliation(s)
- Dennis S Kim
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Michael Xu
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - James M LeBeau
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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3
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Shen Y, Zhang C, Wang Q. Type-1 Pentagonal Tiling Realized in 2D Penta-SrP 2 Sheet. J Phys Chem Lett 2023; 14:8734-8740. [PMID: 37737655 DOI: 10.1021/acs.jpclett.3c02329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/23/2023]
Abstract
According to the systematic classification of pentagon-based two-dimensional (2D) materials [ Phys. Rep. 2022, 964, 1], only type-2 and type-4 out of the 15 pentagonal tiling patterns have been realized in 2D materials so far. Here, we propose the first stable pentagon-based 2D material characterized by the type-1 pentagonal tiling pattern named penta-SrP2. We find that penta-SrP2 is not only thermally and mechanically stable but also dynamically stable when the temperature is above 200 K derived from the calculations by taking both phonon renormalization and thermal expansion into consideration. Moreover, the penta-SrP2 sheet is semiconducting with an indirect band gap of 0.96 eV. These findings expand the family of pentagon-based 2D materials in morphology and provide a new perspective to explore the dynamical stability of high-temperature phases.
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Affiliation(s)
- Yiheng Shen
- Materials Genome Institute, Shanghai University, Shanghai 200444, China
- School of Materials Science and Engineering, CAPT, BKL-MEMD, Peking University, Beijing 100871, China
| | - Chenxin Zhang
- School of Materials Science and Engineering, CAPT, BKL-MEMD, Peking University, Beijing 100871, China
| | - Qian Wang
- School of Materials Science and Engineering, CAPT, BKL-MEMD, Peking University, Beijing 100871, China
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4
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Cheng B, Kramer PL, Shen ZX, Hoffmann MC. Terahertz-Driven Local Dipolar Correlation in a Quantum Paraelectric. PHYSICAL REVIEW LETTERS 2023; 130:126902. [PMID: 37027861 DOI: 10.1103/physrevlett.130.126902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 02/22/2023] [Indexed: 06/19/2023]
Abstract
Light-induced ferroelectricity in quantum paraelectrics is a new avenue of achieving dynamic stabilization of hidden orders in quantum materials. In this Letter, we explore the possibility of driving a transient ferroelectric phase in the quantum paraelectric KTaO_{3} via intense terahertz excitation of the soft mode. We observe a long-lived relaxation in the terahertz-driven second harmonic generation (SHG) signal that lasts up to 20 ps at 10 K, which may be attributed to light-induced ferroelectricity. Through analyzing the terahertz-induced coherent soft-mode oscillation and finding its hardening with fluence well described by a single-well potential, we demonstrate that intense terahertz pulses up to 500 kV/cm cannot drive a global ferroelectric phase in KTaO_{3}. Instead, we find the unusual long-lived relaxation of the SHG signal comes from a terahertz-driven moderate dipolar correlation between the defect-induced local polar structures. We discuss the impact of our findings on current investigations of the terahertz-induced ferroelectric phase in quantum paraelectrics.
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Affiliation(s)
- Bing Cheng
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Patrick L Kramer
- Laser Science and Technology, SLAC Linear Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Zhi-Xun Shen
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
- Departments of Physics and Applied Physics, Stanford University, Stanford, California 94305, USA
| | - Matthias C Hoffmann
- Laser Science and Technology, SLAC Linear Accelerator Laboratory, Menlo Park, California 94025, USA
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5
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Song C, Yang Q, Liu X, Zhao H, Zhang C, Meng S. Electronic Origin of Laser-Induced Ferroelectricity in SrTiO 3. J Phys Chem Lett 2023; 14:576-583. [PMID: 36633437 DOI: 10.1021/acs.jpclett.2c03078] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Although ultrafast control of the nonthermally driven ferroelectric transition of paraelectric SrTiO3 was achieved under laser excitation, the underlying mechanism and dynamics of the photoinduced phase transition remain ambiguous. Here, the determinant formation mechanism of ultrafast ferroelectricity in SrTiO3 is traced by nonadiabatic dynamics simulations. That is, the selective excitation of multiple phonons, induced by photoexcited electrons through the strong correlation between electronic excitation and lattice distortion, results in the breaking of the crystal central symmetry and the onset of ferroelectricity. The accompanying population transition between 3dz2 and 3dx2-y2 orbitals excites multiple phonon branches, including the two high-energy longitudinal optical modes, so as to drive the titanium ion away from the center of the oxygen octahedron and generate a metastable ferroelectric phase. Our findings reveal a cooperative electronic and ionic driving mechanism for the laser-induced ferroelectricity that provides new schemes for the optical control of ultrafast quantum states.
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Affiliation(s)
- Chenchen Song
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing100049, China
| | - Qing Yang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing100190, China
| | - Xinbao Liu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing100049, China
| | - Hui Zhao
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing100049, China
| | - Cui Zhang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing100190, China
- Songshan Lake Materials Laboratory, Dongguan523808, China
| | - Sheng Meng
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing100049, China
- Songshan Lake Materials Laboratory, Dongguan523808, China
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6
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Shin D, Latini S, Schäfer C, Sato SA, Baldini E, De Giovannini U, Hübener H, Rubio A. Simulating Terahertz Field-Induced Ferroelectricity in Quantum Paraelectric SrTiO_{3}. PHYSICAL REVIEW LETTERS 2022; 129:167401. [PMID: 36306771 DOI: 10.1103/physrevlett.129.167401] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 04/19/2022] [Accepted: 09/01/2022] [Indexed: 06/16/2023]
Abstract
Recent experiments have demonstrated that light can induce a transition from the quantum paraelectric to the ferroelectric phase of SrTiO_{3}. Here, we investigate this terahertz field-induced ferroelectric phase transition by solving the time-dependent lattice Schrödinger equation based on first-principles calculations. We find that ferroelectricity originates from a light-induced mixing between ground and first excited lattice states in the quantum paraelectric phase. In agreement with the experimental findings, our study shows that the nonoscillatory second harmonic generation signal can be evidence of ferroelectricity in SrTiO_{3}. We reveal the microscopic details of this exotic phase transition and highlight that this phenomenon is a unique behavior of the quantum paraelectric phase.
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Affiliation(s)
- Dongbin Shin
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free Electron Laser Science, 22761 Hamburg, Germany
| | - Simone Latini
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free Electron Laser Science, 22761 Hamburg, Germany
| | - Christian Schäfer
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free Electron Laser Science, 22761 Hamburg, Germany
- Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, 412 96 Göteborg, Sweden
| | - Shunsuke A Sato
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free Electron Laser Science, 22761 Hamburg, Germany
- Center for Computational Sciences, University of Tsukuba, Tsukuba 305-8577, Japan
| | - Edoardo Baldini
- Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA
| | - Umberto De Giovannini
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free Electron Laser Science, 22761 Hamburg, Germany
- Universitá degli Studi di Palermo, Dipartimento di Fisica e Chimica-Emilio Segrè, via Archirafi 36, I-90123 Palermo, Italy
| | - Hannes Hübener
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free Electron Laser Science, 22761 Hamburg, Germany
| | - Angel Rubio
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free Electron Laser Science, 22761 Hamburg, Germany
- Nano-Bio Spectroscopy Group, Departamento de Fisica de Materiales, Universidad del País Vasco UPV/EHU, 20018 San Sebastián, Spain
- Center for Computational Quantum Physics (CCQ), The Flatiron Institute, 162 Fifth Avenue, New York, New York 10010, USA
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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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Bellini V, Rusponi S, Kolorenč J, Mahatha SK, Valbuena MA, Persichetti L, Pivetta M, Sorokin BV, Merk D, Reynaud S, Sblendorio D, Stepanow S, Nistor C, Gargiani P, Betto D, Mugarza A, Gambardella P, Brune H, Carbone C, Barla A. Slow Magnetic Relaxation of Dy Adatoms with In-Plane Magnetic Anisotropy on a Two-Dimensional Electron Gas. ACS NANO 2022; 16:11182-11193. [PMID: 35770912 PMCID: PMC9330770 DOI: 10.1021/acsnano.2c04048] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We report on the magnetic properties of Dy atoms adsorbed on the (001) surface of SrTiO3. X-ray magnetic circular dichroism reveals slow relaxation of the Dy magnetization on a time scale of about 800 s at 2.5 K, unusually associated with an easy-plane magnetic anisotropy. We attribute these properties to Dy atoms occupying hollow adsorption sites on the TiO2-terminated surface. Conversely, Ho atoms adsorbed on the same surface show paramagnetic behavior down to 2.5 K. With the help of atomic multiplet simulations and first-principles calculations, we establish that Dy populates also the top-O and bridge sites on the coexisting SrO-terminated surface. A simple magnetization relaxation model predicts these two sites to have an even longer magnetization lifetime than the hollow site. Moreover, the adsorption of Dy on the insulating SrTiO3 crystal leads, regardless of the surface termination, to the formation of a spin-polarized two-dimensional electron gas of Ti 3dxy character, together with an antiferromagnetic Dy-Ti coupling. Our findings support the feasibility of tuning the magnetic properties of the rare-earth atoms by acting on the substrate electronic gas with electric fields.
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Affiliation(s)
- Valerio Bellini
- S3-Istituto
di Nanoscienze-CNR, Via
Campi 213/A, I-41125 Modena, Italy
| | - Stefano Rusponi
- Institute
of Physics, Ecole Polytechnique Fédérale de Lausanne
(EPFL), Station 3, CH-1015 Lausanne, Switzerland
| | - Jindřich Kolorenč
- Institute
of Physics (FZU), Czech Academy of Sciences, Na Slovance 2, CZ-182
21 Prague, Czech Republic
| | - Sanjoy K. Mahatha
- Istituto
di Struttura della Materia (ISM), Consiglio Nazionale delle Ricerche
(CNR), I-34149 Trieste, Italy
- School
of
Physics and Materials Science, Thapar Institute
of Engineering and Technology, Patiala 147004, India
| | - Miguel Angel Valbuena
- Catalan
Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST,
Campus UAB, Bellaterra, E-08193 Barcelona, Spain
- Instituto
Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanoscience), E-28049 Madrid, Spain
| | - Luca Persichetti
- Department
of Materials, ETH Zurich, CH-8093 Zurich, Switzerland
- Dipartimento
di Fisica, Università di Roma “Tor
Vergata”, I-00133 Roma, Italy
| | - Marina Pivetta
- Institute
of Physics, Ecole Polytechnique Fédérale de Lausanne
(EPFL), Station 3, CH-1015 Lausanne, Switzerland
| | - Boris V. Sorokin
- Institute
of Physics, Ecole Polytechnique Fédérale de Lausanne
(EPFL), Station 3, CH-1015 Lausanne, Switzerland
| | - Darius Merk
- Institute
of Physics, Ecole Polytechnique Fédérale de Lausanne
(EPFL), Station 3, CH-1015 Lausanne, Switzerland
| | - Sébastien Reynaud
- Institute
of Physics, Ecole Polytechnique Fédérale de Lausanne
(EPFL), Station 3, CH-1015 Lausanne, Switzerland
| | - Dante Sblendorio
- Institute
of Physics, Ecole Polytechnique Fédérale de Lausanne
(EPFL), Station 3, CH-1015 Lausanne, Switzerland
| | | | - Corneliu Nistor
- Department
of Materials, ETH Zurich, CH-8093 Zurich, Switzerland
| | | | - Davide Betto
- European
Synchrotron Radiation Facility, F-38043 Grenoble Cedex, France
| | - Aitor Mugarza
- Catalan
Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST,
Campus UAB, Bellaterra, E-08193 Barcelona, Spain
- Institució
Catalana de Recerca i Estudis Avançats (ICREA), Barcelona E-08010, Spain
| | | | - Harald Brune
- Institute
of Physics, Ecole Polytechnique Fédérale de Lausanne
(EPFL), Station 3, CH-1015 Lausanne, Switzerland
| | - Carlo Carbone
- Istituto
di Struttura della Materia (ISM), Consiglio Nazionale delle Ricerche
(CNR), I-34149 Trieste, Italy
| | - Alessandro Barla
- Istituto
di Struttura della Materia (ISM), Consiglio Nazionale delle Ricerche
(CNR), I-34149 Trieste, Italy
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9
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Dong T, Zhang SJ, Wang NL. Recent Development of Ultrafast Optical Characterizations for Quantum Materials. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022:e2110068. [PMID: 35853841 DOI: 10.1002/adma.202110068] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 06/09/2022] [Indexed: 06/15/2023]
Abstract
The advent of intense ultrashort optical pulses spanning a frequency range from terahertz to the visible has opened a new era in the experimental investigation and manipulation of quantum materials. The generation of strong optical field in an ultrashort time scale enables the steering of quantum materials nonadiabatically, inducing novel phenomenon or creating new phases which may not have an equilibrium counterpart. Ultrafast time-resolved optical techniques have provided rich information and played an important role in characterization of the nonequilibrium and nonlinear properties of solid systems. Here, some of the recent progress of ultrafast optical techniques and their applications to the detection and manipulation of physical properties in selected quantum materials are reviewed. Specifically, the new development in the detection of the Higgs mode and photoinduced nonequilibrium response in the study of superconductors by time-resolved terahertz spectroscopy are discussed.
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Affiliation(s)
- Tao Dong
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
| | - Si-Jie Zhang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
| | - Nan-Lin Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing, 100871, China
- Beijing Academy of Quantum Information Sciences, Beijing, 100913, China
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10
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Yue J, Ayino Y, Truttmann TK, Gastiasoro MN, Persky E, Khanukov A, Lee D, Thoutam LR, Kalisky B, Fernandes RM, Pribiag VS, Jalan B. Anomalous transport in high-mobility superconducting SrTiO 3 thin films. SCIENCE ADVANCES 2022; 8:eabl5668. [PMID: 35613270 PMCID: PMC9132441 DOI: 10.1126/sciadv.abl5668] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 04/08/2022] [Indexed: 06/15/2023]
Abstract
The study of subtle effects on transport in semiconductors requires high-quality epitaxial structures with low defect density. Using hybrid molecular beam epitaxy (MBE), SrTiO3 films with a low-temperature mobility exceeding 42,000 cm2 V-1 s-1 at a low carrier density of 3 × 1017 cm-3 were achieved. A sudden and sharp decrease in residual resistivity accompanied by an enhancement in the superconducting transition temperature were observed across the second Lifshitz transition where the third band becomes occupied, revealing dominant intraband scattering. These films further revealed an anomalous behavior in the Hall carrier density as a consequence of the antiferrodistortive (AFD) transition and the temperature dependence of the Hall scattering factor. Using hybrid MBE growth, phenomenological modeling, temperature-dependent transport measurements, and scanning superconducting quantum interference device imaging, we provide critical insights into the important role of inter- versus intraband scattering and of AFD domain walls on normal-state and superconducting properties of SrTiO3.
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Affiliation(s)
- Jin Yue
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - Yilikal Ayino
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
| | - Tristan K. Truttmann
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - Maria N. Gastiasoro
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
| | - Eylon Persky
- Department of Physics and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Alex Khanukov
- Department of Physics and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Dooyong Lee
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - Laxman R. Thoutam
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - Beena Kalisky
- Department of Physics and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Rafael M. Fernandes
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
| | - Vlad S. Pribiag
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
| | - Bharat Jalan
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA
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11
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Cohen A, Brenner TM, Klarbring J, Sharma R, Fabini DH, Korobko R, Nayak PK, Hellman O, Yaffe O. Diverging Expressions of Anharmonicity in Halide Perovskites. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2107932. [PMID: 35076969 DOI: 10.1002/adma.202107932] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 01/19/2022] [Indexed: 06/14/2023]
Abstract
Lead-based halide perovskite crystals are shown to have strongly anharmonic structural dynamics. This behavior is important because it may be the origin of their exceptional photovoltaic properties. The double perovskite, Cs2 AgBiBr6 , has been recently studied as a lead-free alternative for optoelectronic applications. However, it does not exhibit the excellent photovoltaic activity of the lead-based halide perovskites. Therefore, to explore the correlation between the anharmonic structural dynamics and optoelectronic properties in lead-based halide perovskites, the structural dynamics of Cs2 AgBiBr6 are investigated and are compared to its lead-based analog, CsPbBr3 . Using temperature-dependent Raman measurements, it is found that both materials are indeed strongly anharmonic. Nonetheless, the expression of their anharmonic behavior is markedly different. Cs2 AgBiBr6 has well-defined normal modes throughout the measured temperature range, while CsPbBr3 exhibits a complete breakdown of the normal-mode picture above 200 K. It is suggested that the breakdown of the normal-mode picture implies that the average crystal structure may not be a proper starting point to understand the electronic properties of the crystal. In addition to our main findings, an unreported phase of Cs2 AgBiBr6 is also discovered below ≈37 K.
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Affiliation(s)
- Adi Cohen
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Thomas M Brenner
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Johan Klarbring
- Theoretical Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping, SE-581 83, Sweden
| | - Rituraj Sharma
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Douglas H Fabini
- Max Planck Institute for Solid State Research, 70569, Stuttgart, Germany
| | - Roman Korobko
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Pabitra K Nayak
- Tata Institute of Fundamental Research, Hyderabad, 500046, India
| | - Olle Hellman
- Theoretical Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping, SE-581 83, Sweden
| | - Omer Yaffe
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, 76100, Israel
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12
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Kaviani M, Aschauer U. Surface and interface effects in oxygen-deficient SrMnO3 thin films grown on SrTiO3. Phys Chem Chem Phys 2022; 24:3951-3957. [PMID: 35099494 PMCID: PMC8827045 DOI: 10.1039/d1cp04998d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Complex oxide functionality, such as ferroelectricity, magnetism or superconductivity is often achieved in epitaxial thin-film geometries. Oxygen vacancies tend to be the dominant type of defect in these materials but a fundamental understanding of their stability and electronic structure has so far mostly been established in the bulk or strained bulk, neglecting interfaces and surfaces present in a thin-film geometry. We investigate here, via density functional theory calculations, oxygen vacancies in the model system of a SrMnO3 (SMO) thin film grown on a SrTiO3 (STO) (001) substrate. Structural and electronic differences compared to bulk SMO result mainly from undercoordination at the film surface. The changed crystal field leads to a depletion of subsurface valence-band states and transfer of this charge to surface Mn atoms, both of which strongly affect the defect chemistry in the film. The result is a strong preference of oxygen vacancies in the surface region compared to deeper layers. Finally, for metastable oxygen vacancies in the substrate, we predict a spatial separation of the defect from its excess charge, the latter being accommodated in the film but close to the substrate boundary. These results show that surface and interface effects lead to significant differences in stability and electronic structure of oxygen vacancies in thin-film geometries compared to the (strained) bulk. The oxygen vacancy formation energy in an SrMnO3 thin film grown on a SrTiO3 substrate is affected by crystal-field effects at the very surface and the induced electrostatic potential.![]()
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Affiliation(s)
- Moloud Kaviani
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Ulrich Aschauer
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
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13
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Guedes EB, Muff S, Brito WH, Caputo M, Li H, Plumb NC, Dil JH, Radović M. Universal Structural Influence on the 2D Electron Gas at SrTiO 3 Surfaces. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2100602. [PMID: 34532983 PMCID: PMC8596100 DOI: 10.1002/advs.202100602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 06/23/2021] [Indexed: 05/28/2023]
Abstract
The 2-dimensional electron gas (2DEG) found at the surface of SrTiO3 and related interfaces has attracted significant attention as a promising basis for oxide electronics. In order to utilize its full potential, the response of this 2DEG to structural changes and surface modification must be understood in detail. Here, a study of the detailed electronic structure evolution of the 2DEG as a function of sample temperature and surface step density is presented. By comparing the experimental results with ab initio calculations, it is shown that local structure relaxations cause a metal-insulator transition of the system around 135 K. This study presents a new and simple way of tuning the 2DEG via surface vicinality and identifies how the operation of prospective devices will respond to changes in temperature.
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Affiliation(s)
- Eduardo B. Guedes
- Photon Science DivisionPaul Scherrer InstitutVilligenCH‐5232Switzerland
| | - Stefan Muff
- Photon Science DivisionPaul Scherrer InstitutVilligenCH‐5232Switzerland
| | - Walber H. Brito
- Departamento de FísicaUniversidade Federal de Minas GeraisC.P. 702Belo HorizonteMinas Gerais30123Brazil
| | - Marco Caputo
- Photon Science DivisionPaul Scherrer InstitutVilligenCH‐5232Switzerland
- Elettra‐Sincrotrone TriesteS.C.p.A, S.S 14‐km 163.5 in AREA Science Park, BasovizzaTrieste34149Italy
| | - Hang Li
- Photon Science DivisionPaul Scherrer InstitutVilligenCH‐5232Switzerland
- Department of Energy Conversion and StorageTechnical University of DenmarkKgs. Lyngby2800Denmark
| | - Nicholas C. Plumb
- Photon Science DivisionPaul Scherrer InstitutVilligenCH‐5232Switzerland
| | - J. Hugo Dil
- Photon Science DivisionPaul Scherrer InstitutVilligenCH‐5232Switzerland
- Institut de PhysiqueÉcole Polytechnique Fédérale de LausanneLausanneCH‐1015Switzerland
| | - Milan Radović
- Photon Science DivisionPaul Scherrer InstitutVilligenCH‐5232Switzerland
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14
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Tkach A, Okhay O, Nuzhnyy D, Petzelt J, Vilarinho PM. Polar Phonon Behaviour in Polycrystalline Bi-Doped Strontium Titanate Thin Films. MATERIALS 2021; 14:ma14216414. [PMID: 34771941 PMCID: PMC8585388 DOI: 10.3390/ma14216414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 10/14/2021] [Accepted: 10/21/2021] [Indexed: 11/16/2022]
Abstract
Strontium titanate-based materials with ferroelectric or relaxor-like properties have drawn vast attention as polar dielectrics for electronics and telecommunications. Here, we study the lattice dynamics in sol–gel-derived Sr1−1.5xBixTiO3 thin films with x = 0.0053 and 0.167, deposited on Al2O3 substrates, using a variable-temperature far-infrared spectroscopy in a transmittance mode. Bi doping, known to induce a low-frequency dielectric relaxation in SrTiO3 (ST) ceramics and films, due to off-centre dopant ion displacements generating electric dipoles, is shown to affect the polar phonon behaviour of thin films. We show that in weakly Bi-doped films, the low-frequency polar TO1 mode softens on cooling but less than in undoped ST. In heavily Bi-doped ST films, this mode displays no significant frequency variation with temperature from 300 to 10 K. The polar phonon behaviour of polycrystalline Bi-doped ST thin films is comparable with that of Bi-doped ST ceramics, which exhibit dielectric relaxations and harden soft-mode behaviour instead of the ferroelectric phase transition.
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Affiliation(s)
- Alexander Tkach
- Department of Materials and Ceramic Engineering, CICECO–Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, Portugal; (A.T.); (P.M.V.)
| | - Olena Okhay
- TEMA-Centre for Mechanical Technology and Automation, Department of Mechanical Engineering, University of Aveiro, 3810-193 Aveiro, Portugal
- Correspondence:
| | - Dmitry Nuzhnyy
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 21 Prague, Czech Republic; (D.N.); (J.P.)
| | - Jan Petzelt
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 21 Prague, Czech Republic; (D.N.); (J.P.)
| | - Paula M. Vilarinho
- Department of Materials and Ceramic Engineering, CICECO–Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, Portugal; (A.T.); (P.M.V.)
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15
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Han B, Zhu R, Li X, Wu M, Ishikawa R, Feng B, Bai X, Ikuhara Y, Gao P. Two-Dimensional Room-Temperature Giant Antiferrodistortive SrTiO_{3} at a Grain Boundary. PHYSICAL REVIEW LETTERS 2021; 126:225702. [PMID: 34152191 DOI: 10.1103/physrevlett.126.225702] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 04/23/2021] [Indexed: 06/13/2023]
Abstract
The broken symmetry at structural defects such as grain boundaries (GBs) discontinues chemical bonds, leading to the emergence of new properties that are absent in the bulk owing to the couplings between the lattice and other parameters. Here, we create a two-dimensional antiferrodistortive (AFD) strontium titanate (SrTiO_{3}) phase at a Σ13(510)/[001] SrTiO_{3} tilt GB at room temperature. We find that such an anomalous room-temperature AFD phase with the thickness of approximate six unit cells is stabilized by the charge doping from oxygen vacancies. The localized AFD originated from the strong lattice-charge couplings at a SrTiO_{3} GB is expected to play important roles in the electrical and optical activity of GBs and can explain past experiments such as the transport properties of electroceramic SrTiO_{3}. Our study also provides new strategies to create low-dimensional anomalous elements for future nanoelectronics via grain boundary engineering.
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Affiliation(s)
- Bo Han
- Electron Microscopy Laboratory and International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Ruixue Zhu
- Electron Microscopy Laboratory and International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Xiaomei Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Mei Wu
- Electron Microscopy Laboratory and International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Ryo Ishikawa
- Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
- Japan Science and Technology Agency, PRESTO, Kawaguchi, Saitama 332-0012, Japan
| | - Bin Feng
- Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
| | - Xuedong Bai
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Yuichi Ikuhara
- Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
- Nanostructures Research Laboratory, Japan Fine Ceramic Center, Nagoya 456-8587, Japan
- WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - Peng Gao
- Electron Microscopy Laboratory and International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials, Peking University, Beijing 100871, China
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16
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Casella L, Zaccone A. Soft mode theory of ferroelectric phase transitions in the low-temperature phase. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:165401. [PMID: 33440364 DOI: 10.1088/1361-648x/abdb68] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 01/13/2021] [Indexed: 06/12/2023]
Abstract
Historically, the soft mode theory of ferroelectric phase transitions has been developed for the high-temperature (paraelectric) phase, where the phonon mode softens upon decreasing the temperature. In the low-temperature ferroelectric phase, a similar phonon softening occurs, also leading to a bosonic condensation of the frozen-in mode at the transition, but in this case the phonon softening occurs upon increasing the temperature. Here we present a soft mode theory of ferroelectric and displacive phase transitions by describing what happens in the low-temperature phase in terms of phonon softening and instability. A new derivation of the generalized Lyddane-Sachs-Teller (LST) relation for materials with strong anharmonic phonon damping is also presented which leads to the expressionɛ0/ɛ∞= |ωLO|2/|ωTO|2. The theory provides a microscopic expression forTcas a function of physical parameters, including the mode specific Grüneisen parameter. The theory also shows thatωTO∼(Tc-T)1/2, and again specifies the prefactors in terms of Grüneisen parameter and fundamental physical constants. Using the generalized LST relation, the softening of the TO mode leads to the divergence ofϵ0and to a polarization catastrophe atTc. A quantitative microscopic form of the Curie-Weiss law is derived with prefactors that depend on microscopic physical parameters.
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Affiliation(s)
- Luigi Casella
- Department of Physics 'A Pontremoli', University of Milan, via Celoria 16, 20133 Milan, Italy
| | - Alessio Zaccone
- Department of Physics 'A Pontremoli', University of Milan, via Celoria 16, 20133 Milan, Italy
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, CB30HE Cambridge, United Kingdom
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17
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Abstract
SrTiO3 is an insulating material which, using chemical doping, pressure, strain or isotope substitution, can be turned into a ferroelectric material or into a superconductor. The material itself, and the two aforementioned phenomena, have been subjects of intensive research of Karl Alex Müller and have been a source of inspiration, among other things, for his Nobel prize-winning research on high temperature superconductivity. An intriguing outstanding question is whether the occurrence of ferroelectricity and superconductivity in the same material is just a coincidence, or whether a deeper connection exists. In addition there is the empirical question of how these two phenomena interact with each other. Here we show that it is possible to induce superconductivity in a two-dimensional layer at the interface of SrTiO3 and LaAlO3 when we make the SrTiO3 ferroelectric by means of 18O substitution. Our experiments indicate that the ferroelectricity is perfectly compatible with having a superconducting two-dimensional electron system at the interface. This provides a promising avenue for manipulating superconductivity in a non centrosymmetric environment.
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18
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Zhang B, Wu L, Feng X, Li C, Miao X, Hui Y, Zhao K, Ding J, Jin B, Chen J, Zhu Y, Sun CJ, Chow GM. Tuning Irreversible Magnetoresistance in Pr 0.67Sr 0.33MnO 3 Film via Octahedral Rotation. ACS APPLIED MATERIALS & INTERFACES 2020; 12:43222-43230. [PMID: 32820885 DOI: 10.1021/acsami.0c10402] [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
The oxygen octahedral rotation around the out-of-plane axis is explored to study its effect on metastable status, magnetic cluster glass in manganite. The antiphase rotation around the out-of-plane axis (TiO6 a0a0c-) of SrTiO3 enhances the Mn-O bond anisotropy along in-plane and out-of-plane directions and weakens the ferromagnetic interactions in a 12 nm Pr0.67Sr0.33MnO3 film on the (001) SrTiO3 substrate, which together promote the formation of magnetic cluster-glassiness and enlarges the irreversible magnetoresistance (MR) effect with enhanced relaxation time of charge carriers. The effect of TiO6 a0a0c- in the SrTiO3 substrate on material properties is obvious with a large irreversible MR effect for thin films, which fades away with the increase in film thickness. At 10 K, the irreversible MR is 0.91 for the 12 nm film and 0.22 for the 30 nm film. This work extends current understanding on interfacial coupling to metastable status and could help explore other systems in the perovskite structure with octahedral rotation.
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Affiliation(s)
- Bangmin Zhang
- Centre for Physical Mechanics and Biophysics, School of Physics, Sun Yat-sen University, Guangzhou 510275, China
| | - Lijun Wu
- Condensed Matter Physics & Materials Science Division, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Xin Feng
- Department of Materials Science & Engineering, National University of Singapore, 117575, Singapore
| | - Chun Li
- Research Institute of Superconductor Electronics (RISE), School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
| | - Xinyang Miao
- Petroleum and Chemical Industry Federation Key Laboratory of Oil and Gas Terahertz Spectroscopy and Photoelectric Detection, China University of Petroleum, Beijing 102249, China
| | - Yajuan Hui
- Department of Materials Science & Engineering, National University of Singapore, 117575, Singapore
| | - Kun Zhao
- Petroleum and Chemical Industry Federation Key Laboratory of Oil and Gas Terahertz Spectroscopy and Photoelectric Detection, China University of Petroleum, Beijing 102249, China
| | - Jun Ding
- Department of Materials Science & Engineering, National University of Singapore, 117575, Singapore
| | - Biaobing Jin
- Research Institute of Superconductor Electronics (RISE), School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
| | - Jingsheng Chen
- Department of Materials Science & Engineering, National University of Singapore, 117575, Singapore
| | - Yimei Zhu
- Condensed Matter Physics & Materials Science Division, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Cheng-Jun Sun
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Gan Moog Chow
- Department of Materials Science & Engineering, National University of Singapore, 117575, Singapore
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19
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Lanigan-Atkins T, Yang S, Niedziela JL, Bansal D, May AF, Puretzky AA, Lin JYY, Pajerowski DM, Hong T, Chi S, Ehlers G, Delaire O. Extended anharmonic collapse of phonon dispersions in SnS and SnSe. Nat Commun 2020; 11:4430. [PMID: 32887880 PMCID: PMC7474096 DOI: 10.1038/s41467-020-18121-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Accepted: 08/09/2020] [Indexed: 11/12/2022] Open
Abstract
The lattice dynamics and high-temperature structural transition in SnS and SnSe are investigated via inelastic neutron scattering, high-resolution Raman spectroscopy and anharmonic first-principles simulations. We uncover a spectacular, extreme softening and reconstruction of an entire manifold of low-energy acoustic and optic branches across a structural transition, reflecting strong directionality in bonding strength and anharmonicity. Further, our results solve a prior controversy by revealing the soft-mode mechanism of the phase transition that impacts thermal transport and thermoelectric efficiency. Our simulations of anharmonic phonon renormalization go beyond low-order perturbation theory and capture these striking effects, showing that the large phonon shifts directly affect the thermal conductivity by altering both the phonon scattering phase space and the group velocities. These results provide a detailed microscopic understanding of phase stability and thermal transport in technologically important materials, providing further insights on ways to control phonon propagation in thermoelectrics, photovoltaics, and other materials requiring thermal management.
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Affiliation(s)
- T Lanigan-Atkins
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC, USA
| | - S Yang
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC, USA
| | - J L Niedziela
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - D Bansal
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC, USA
| | - A F May
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - A A Puretzky
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - J Y Y Lin
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - D M Pajerowski
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - T Hong
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - S Chi
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - G Ehlers
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - O Delaire
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC, USA.
- Department of Physics, Duke University, Durham, NC, USA.
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20
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Stock C, Songvilay M, Gehring PM, Xu G, Roessli B. Broadband critical dynamics in disordered lead-based perovskites. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:374012. [PMID: 32252031 DOI: 10.1088/1361-648x/ab86ee] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 04/06/2020] [Indexed: 06/11/2023]
Abstract
Materials based on the cubic perovskite unit cell continue to provide the basis for technologically important materials with two notable recent examples being lead-based relaxor piezoelectrics and lead-based organic-inorganic halide photovoltaics. These materials carry considerable disorder, arising from site substitution in relaxors and molecular vibrations in the organic-inorganics, yet much of our understanding of these systems derives from the initial classic work of Prof. Roger A Cowley, who applied both theory and neutron scattering methods while at Chalk River Laboratories to the study of lattice vibrations in SrTiO3. Neutron scattering continues to play a vital role in characterizing lattice vibrations in perovskites owing to the simple cross section and the wide range of energy resolutions achievable with current neutron instrumentation. We discuss the dynamics that drive the phase transitions in the relaxors and organic-inorganic lead-halides in terms of neutron scattering and compare them to those in phase transitions associated with a 'central peak' and also a soft mode. We review some of the past experimental work on these materials and present new data from high-resolution time-of-flight backscattering spectroscopy taken on organic-inorganic perovskites. We will show that the structural transitions in disordered lead-based perovskites are driven by a broad frequency band of excitations.
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Affiliation(s)
- C Stock
- School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
| | - M Songvilay
- School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
| | - P M Gehring
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland, 20899, United States of America
| | - Guangyong Xu
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland, 20899, United States of America
| | - B Roessli
- Laboratory for Neutron Scattering and Imaging (LNS), Paul Scherrer Institute (PSI), 5232 Villigen PSI, Switzerland
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21
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He X, Bansal D, Winn B, Chi S, Boatner L, Delaire O. Anharmonic Eigenvectors and Acoustic Phonon Disappearance in Quantum Paraelectric SrTiO_{3}. PHYSICAL REVIEW LETTERS 2020; 124:145901. [PMID: 32338961 DOI: 10.1103/physrevlett.124.145901] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 01/19/2020] [Accepted: 03/16/2020] [Indexed: 06/11/2023]
Abstract
Pronounced anomalies in the SrTiO_{3} dynamical structure factor, S(Q,E), including the disappearance of acoustic phonon branches at low temperatures, were uncovered with inelastic neutron scattering (INS) and simulations. The striking effect reflects anharmonic couplings between acoustic and optic phonons and the incipient ferroelectric instability near the quantum critical point. It is rationalized using a first-principles renormalized anharmonic phonon approach, pointing to nonlinear Ti-O hybridization causing unusual changes in real-space phonon eigenvectors, frequencies, group velocities, and scattering phase space. Our method is general and establishes how T dependences beyond the harmonic regime, assessed by INS mapping of large reciprocal-space volumes, provide real-space insights into anharmonic atomic dynamics near phase transitions.
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Affiliation(s)
- Xing He
- Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, USA
| | - Dipanshu Bansal
- Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai, Maharashtra 400076, India
| | - Barry Winn
- Neutron Scattering Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Songxue Chi
- Neutron Scattering Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Lynn Boatner
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Olivier Delaire
- Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, USA
- Department of Physics, Duke University, Durham, North Carolina 27708, USA
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
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22
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Nova TF, Disa AS, Fechner M, Cavalleri A. Metastable ferroelectricity in optically strained SrTiO 3. Science 2020; 364:1075-1079. [PMID: 31197010 DOI: 10.1126/science.aaw4911] [Citation(s) in RCA: 107] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 05/20/2019] [Indexed: 11/03/2022]
Abstract
Fluctuating orders in solids are generally considered high-temperature precursors of broken symmetry phases. However, in some cases, these fluctuations persist to zero temperature and prevent the emergence of long-range order. Strontium titanate (SrTiO3) is a quantum paraelectric in which dipolar fluctuations grow upon cooling, although a long-range ferroelectric order never sets in. Here, we show that optical excitation of lattice vibrations can induce polar order. This metastable polar phase, observed up to temperatures exceeding 290 kelvin, persists for hours after the optical pump is interrupted. Furthermore, hardening of a low-frequency vibration points to a photoinduced ferroelectric phase transition, with a spatial domain distribution suggestive of a photoflexoelectric coupling.
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Affiliation(s)
- T F Nova
- Max Planck Institute for the Structure and Dynamics of Matter, Hamburg 22761, Germany. .,The Hamburg Centre for Ultrafast Imaging, Hamburg 22761, Germany
| | - A S Disa
- Max Planck Institute for the Structure and Dynamics of Matter, Hamburg 22761, Germany
| | - M Fechner
- Max Planck Institute for the Structure and Dynamics of Matter, Hamburg 22761, Germany
| | - A Cavalleri
- Max Planck Institute for the Structure and Dynamics of Matter, Hamburg 22761, Germany. .,The Hamburg Centre for Ultrafast Imaging, Hamburg 22761, Germany.,Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
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23
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Li X, Qiu T, Zhang J, Baldini E, Lu J, Rappe AM, Nelson KA. Terahertz field-induced ferroelectricity in quantum paraelectric SrTiO 3. Science 2020; 364:1079-1082. [PMID: 31197011 DOI: 10.1126/science.aaw4913] [Citation(s) in RCA: 114] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 05/20/2019] [Indexed: 11/02/2022]
Abstract
"Hidden phases" are metastable collective states of matter that are typically not accessible on equilibrium phase diagrams. These phases can host exotic properties in otherwise conventional materials and hence may enable novel functionality and applications, but their discovery and access are still in early stages. Using intense terahertz electric field excitation, we found that an ultrafast phase transition into a hidden ferroelectric phase can be dynamically induced in quantum paraelectric strontium titanate (SrTiO3). The induced lowering in crystal symmetry yields substantial changes in the phonon excitation spectra. Our results demonstrate collective coherent control over material structure, in which a single-cycle field drives ions along the microscopic pathway leading directly to their locations in a new crystalline phase on an ultrafast time scale.
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Affiliation(s)
- Xian Li
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Tian Qiu
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jiahao Zhang
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Edoardo Baldini
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jian Lu
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Andrew M Rappe
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Keith A Nelson
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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24
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Wang L, Pan W, Han D, Hu WX, Sun DY. First-principles calculations of oxygen octahedral distortions in LaAlO 3/SrTiO 3(001) superlattices. Phys Chem Chem Phys 2020; 22:5826-5831. [PMID: 32107515 DOI: 10.1039/c9cp06236j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The size, shape and connectivity of oxide octahedra are essential for understanding and controlling the emergent functional properties of ABO3 perovskites. Using first-principles calculations, we systematically studied the oxygen octahedral rotation and deformation in LaAlO3/SrTiO3(001) superlattices. Superlattices with electron- or hole-doped interfaces, or both, are compared. The results showed that there are at least three different types of oxygen octahedral distortions in these superlattices, which is more than what had previously been reported in the literature. We demonstrate that interfacial oxygen octahedral coupling and hole-doping, in addition to epitaxial strain, are the key factors underlying the formation of multiple types of oxygen octahedral rotations in these systems. We confirm that oxygen octahedral rotations and deformations play an essential role in insulator-metal transitions. Furthermore, octahedral distortion leads to ferroelectricity like dipole formation with the polarization vector always pointing to the positively charged interfaces.
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Affiliation(s)
- L Wang
- Department of Physics, East China Normal University, No. 500, Dongchuan Road, Shanghai 200241, People's Republic of China.
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25
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Li X, Fauqué B, Zhu Z, Behnia K. Phonon Thermal Hall Effect in Strontium Titanate. PHYSICAL REVIEW LETTERS 2020; 124:105901. [PMID: 32216396 DOI: 10.1103/physrevlett.124.105901] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 02/20/2020] [Indexed: 06/10/2023]
Abstract
It has been known for more than a decade that phonons can produce an off-diagonal thermal conductivity in the presence of a magnetic field. Recent studies of thermal Hall conductivity, κ_{xy}, in a variety of contexts, however, have assumed a negligibly small phonon contribution. We present a study of κ_{xy} in quantum paraelectric SrTiO_{3}, which is a nonmagnetic insulator and find that its peak value exceeds what has been reported in any other insulator, including those in which the signal has been qualified as "giant." Remarkably, κ_{xy}(T) and κ(T) peak at the same temperature and the former decreases faster than the latter at both sides of the peak. Interestingly, in the case of La_{2}CuO_{4} and α-RuCl_{3}, κ_{xy}(T) and κ(T) peak also at the same temperature. We also studied KTaO_{3} and found a small signal, indicating that a sizable κ_{xy}(T) is not a generic feature of quantum paraelectrics. Combined to other observations, this points to a crucial role played by antiferrodistortive domains in generating κ_{xy} of this solid.
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Affiliation(s)
- Xiaokang Li
- Laboratoire de Physique et d'Etude des Matériaux (CNRS) ESPCI Paris, PSL Research University, 75005 Paris, France
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Benoît Fauqué
- JEIP, USR 3573 CNRS, Collège de France, PSL University, 11, place Marcelin Berthelot, 75231 Paris Cedex 05, France
| | - Zengwei Zhu
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Kamran Behnia
- Laboratoire de Physique et d'Etude des Matériaux (CNRS) ESPCI Paris, PSL Research University, 75005 Paris, France
- II. Physikalisches Institut, Universität zu Köln, 50937 Köln, Germany
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26
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Zvejnieks G, Rusevich LL, Gryaznov D, Kotomin EA. Interface-induced enhancement of piezoelectricity in the (SrTiO 3) m/(BaTiO 3) M-m superlattice for energy harvesting applications. Phys Chem Chem Phys 2019; 21:23541-23551. [PMID: 31617511 DOI: 10.1039/c9cp04086b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present the results of a detailed first principles study of the piezoelectric properties of the (SrTiO3)m/(BaTiO3)M-m heterostructure using the 3D STOm/BTOM-m superlattice model. The atomic basis set, hybrid functionals and slabs with different numbers of STO and BTO layers were used. The interplay between ferroelectric (FEz) and antiferrodistortive (AFDz) displacements is carefully analyzed. Based on the experimental data and group theoretical analysis, we deduce two possible space groups of tetragonal symmetry which allow us to reproduce the experimentally known pure STO and BTO bulk phases in the limiting cases, and to model the corresponding intermediate superlattices. The characteristic feature of the space group P4mm (#99) model is atomic displacements in the [001] direction, which allows us to simulate the FEz displacements, whereas the P4 (#75) model besides FEz displacements permits oxygen octahedra antiphase rotations around the [001] direction and thus AFDz displacements. Our calculations demonstrate that for m/M≤ 0.75 layer ratios both models show similar geometries and piezoelectric constants. Moreover, both models predict an approximately 6-fold increase of the piezoelectric constant e33 compared to the BaTiO3 bulk value, albeit at slightly different layer ratios. The obtained results clearly demonstrate that piezoelectricity arises due to the coordinated collective FEz displacements of atoms in both STO and BTO slabs and interfaces and reaches its maximum when the superlattice approaches the point where the tetragonal phase becomes unstable and transforms to a pseudo-cubic phase. We demonstrate that even a single or double layer of BTO is sufficient to trigger FEz displacements in the STO slab, in P4mm and P4 models, respectively.
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Affiliation(s)
- Guntars Zvejnieks
- Institute of Solid State Physics, University of Latvia, Kengaraga Str. 8, LV-1063 Riga, Latvia.
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27
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Porer M, Fechner M, Bothschafter EM, Rettig L, Narayan A, Radovic M, Savoini M, Esposito V, Rittmann J, Kubli M, Kubacka T, Huber T, Neugebauer M, Abreu E, Grübel S, Beaud P, Ingold G, Lantz G, Parchenko S, Song S, Sato T, Aschauer U, Spaldin N, Johnson SL, Staub U. Optically induced transient enhancement of a structural order parameter. EPJ WEB OF CONFERENCES 2019. [DOI: 10.1051/epjconf/201920507001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We photoexcite SrTiO3 and EuTiO3 in their purely soft-mode-driven structurally distorted phase and trace the structural order parameter via ultra-short x-rays. We observe a rapid decay for SrTiO3 and an intriguing transient enhancement for EuTiO3.
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28
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Occhialini CA, Guzmán-Verri GG, Handunkanda SU, Hancock JN. Negative Thermal Expansion Near the Precipice of Structural Stability in Open Perovskites. Front Chem 2018; 6:545. [PMID: 30515376 PMCID: PMC6255880 DOI: 10.3389/fchem.2018.00545] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2018] [Accepted: 10/19/2018] [Indexed: 11/13/2022] Open
Abstract
Negative thermal expansion (NTE) describes the anomalous propensity of materials to shrink when heated. Since its discovery, the NTE effect has been found in a wide variety of materials with an array of magnetic, electronic and structural properties. In some cases, the NTE originates from phase competition arising from the electronic or magnetic degrees of freedom but we here focus on a particular class of NTE which originates from intrinsic dynamical origins related to the lattice degrees of freedom, a property we term structural negative thermal expansion (SNTE). Here we review some select cases of NTE which strictly arise from anharmonic phonon dynamics, with a focus on open perovskite lattices. We find that NTE is often present close in proximity to competing structural phases, with structural phase transition lines terminating near T=0 K yielding the most prominent displays of the SNTE effect. We further provide a theoretical model to make precise the proposed relationship among the signature behavior of SNTE, the proximity of these systems to structural quantum phase transitions and the effects of phase fluctuations near these unique regions of the structural phase diagram. The effects of compositional disorder on NTE and structural phase stability in perovskites are discussed.
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Affiliation(s)
- Connor A Occhialini
- Department of Physics, University of Connecticut, Storrs, CT, United States.,Institute of Materials Science, University of Connecticut, Storrs, CT, United States
| | - Gian G Guzmán-Verri
- Centro de Investigación en Ciencia e Ingeniería de Materiales, Universidad de Costa Rica, San José, Costa Rica.,Materials Science Division, Argonne National Laboratory, Argonne, IL, United States
| | - Sahan U Handunkanda
- Department of Physics, University of Connecticut, Storrs, CT, United States.,Institute of Materials Science, University of Connecticut, Storrs, CT, United States
| | - Jason N Hancock
- Department of Physics, University of Connecticut, Storrs, CT, United States.,Institute of Materials Science, University of Connecticut, Storrs, CT, United States
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29
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Songvilay M, Bari M, Ye ZG, Xu G, Gehring PM, Ratcliff WD, Schmalzl K, Bourdarot F, Roessli B, Stock C. Lifetime-shortened acoustic phonons and static order at the Brillouin zone boundary in the organic-inorganic perovskite CH 3NH 3PbCl 3. PHYSICAL REVIEW MATERIALS 2018; 2:10.1103/PhysRevMaterials.2.123601. [PMID: 38915935 PMCID: PMC11194761 DOI: 10.1103/physrevmaterials.2.123601] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
Lead halide hybrid perovskites consist of an inorganic framework hosting a molecular cation located in the interstitial space. These compounds have been extensively studied as they have been identified as promising materials for photovoltaic applications with the interaction between the molecular cation and the inorganic framework implicated as influential for the electronic properties. CH3NH3PbCl3 undergoes two structural transitions from a high temperature cubic unit cell to a tetragonal phase at 177 K and then a subsequent orthorhombic transition at 170 K. We have measured the low-frequency lattice dynamics using neutron spectroscopy and observe an energy broadening in the acoustic phonon linewidth towards the high-symmetry pointQ X = ( 2 , 1 2 , 0 ) when approaching the transitions. Concomitant with these zone boundary anomalies is a hardening of the entire acoustic phonon branch measured in the q → 0 limit near the (2, 0, 0) Bragg position with decreasing temperature. Measurements of the elastic scattering at the Brillouin zone edgesQ X = ( 2 , 1 2 , 0 ) , Q M = ( 3 2 , 1 2 , 0 ) , andQ R = ( 3 2 , 3 2 , 5 2 ) show Bragg peaks appearing below these structural transitions. Based on selection rules of neutron scattering, we suggest that the higher 177 K transition is displacive with a distortion of the local octahedral environment and the lower transition is a rigid tilt transition of the octahedra. We do not observe any critical broadening in energy or momentum, beyond resolution, of these peaks near the transitions. We compare these results to the critical properties reported near the structural transitions in other perovskites and particularly CsPbCl3 [Y. Fujii, S. Hoshino, Y. Yamada, and G. Shirane, Phys. Rev. B 9, 4549 (1974)]. We suggest that the simultaneous onset of static resolution-limited Bragg peaks at the zone boundaries and the changes in acoustic phonon energies near the zone center is evidence of a coupling between the inorganic framework and the molecular cation. The results also highlight the importance of displacive transitions in organic-inorganic hybrid perovskites.
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Affiliation(s)
- M. Songvilay
- School of Physics and Astronomy and Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
| | - M. Bari
- Department of Chemistry and 4D labs, Simon Fraser University, Burnaby, British Columbia, Canada V5A1S6
| | - Z.-G. Ye
- Department of Chemistry and 4D labs, Simon Fraser University, Burnaby, British Columbia, Canada V5A1S6
| | - Guangyong Xu
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
| | - P. M. Gehring
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
| | - W. D. Ratcliff
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
| | - K. Schmalzl
- Jülich Centre for Neutron Science at ILL, Forschungszentrum Jülich GmbH, 71 avenue des Martyrs, 38000 Grenoble, France
| | - F. Bourdarot
- Université Grenoble Alpes, CEA, INAC, MEM/MDN, F-38000 Grenoble, France
| | - B. Roessli
- Laboratory for Neutron Scattering and Imaging (LNS), Paul Scherrer Institut (PSI), 5232 Villigen PSI, Switzerland
| | - C. Stock
- School of Physics and Astronomy and Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
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30
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Coak MJ, Haines CRS, Liu C, Jarvis DM, Littlewood PB, Saxena SS. Dielectric Response of Quantum Critical Ferroelectric as a Function of Pressure. Sci Rep 2018; 8:14936. [PMID: 30297803 PMCID: PMC6175889 DOI: 10.1038/s41598-018-33320-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 09/21/2018] [Indexed: 11/09/2022] Open
Abstract
In this work we report for the first time measurements of the dielectric loss of single-crystal SrTiO3 under the application of hydrostatic pressure up to 20 kbar and temperatures down to 200 mK which allow us to comment on the evolution of new fundamental material properties and their relationship with the recently discovered quantum critical phenomena in this material. The well known 18 K peak or shoulder was no longer observed after pressure was applied, even after subsequently removing it, suggesting it is associated with the twin walls formed at the 110 K cubic-tetragonal transition. The family of familiar peaks were all seen to increase in temperature linearly with pressure and the height of the 9.4 K peak was drastically suppressed by even the smallest pressures. This peak is discussed in the context of a postulated ferroelectric quantum critical point in SrTiO3 and the behaviour of its size linked to the position of this point on the recently established phase diagram.
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Affiliation(s)
- M J Coak
- Cavendish Laboratory, Cambridge University, J. J. Thomson Ave, Cambridge, CB3 0HE, UK. .,Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, Republic of Korea. .,Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea.
| | - C R S Haines
- Cavendish Laboratory, Cambridge University, J. J. Thomson Ave, Cambridge, CB3 0HE, UK.
| | - C Liu
- Cavendish Laboratory, Cambridge University, J. J. Thomson Ave, Cambridge, CB3 0HE, UK
| | - D M Jarvis
- Cavendish Laboratory, Cambridge University, J. J. Thomson Ave, Cambridge, CB3 0HE, UK
| | - P B Littlewood
- Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, Illinois, 60439, United States.,James Franck Institute, University of Chicago, 929 E 57 St., Chicago, Illinois, 60637, USA
| | - S S Saxena
- Cavendish Laboratory, Cambridge University, J. J. Thomson Ave, Cambridge, CB3 0HE, UK. .,National University of Science and Technology " MISiS", Leninsky Prospekt 4, Moscow, 119049, Russia.
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31
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Morozovska AN, Khist VV, Glinchuk MD, Scherbakov CM, Silibin MV, Karpinsky DV, Eliseev EA. Flexoelectricity induced spatially modulated phases in ferroics and liquid crystals. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.01.052] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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32
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Campbell B, Howard CJ, Averett TB, Whittle TA, Schmid S, Machlus S, Yost C, Stokes HT. An algebraic approach to cooperative rotations in networks of interconnected rigid units. Acta Crystallogr A Found Adv 2018; 74:408-424. [PMID: 30182930 DOI: 10.1107/s2053273318009713] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 07/07/2018] [Indexed: 11/10/2022] Open
Abstract
Crystalline solids consisting of three-dimensional networks of interconnected rigid units are ubiquitous amongst functional materials. In many cases, application-critical properties are sensitive to rigid-unit rotations at low temperature, high pressure or specific stoichiometry. The shared atoms that connect rigid units impose severe constraints on any rotational degrees of freedom, which must then be cooperative throughout the entire network. Successful efforts to identify cooperative-rotational rigid-unit modes (RUMs) in crystals have employed split-atom harmonic potentials, exhaustive testing of the rotational symmetry modes allowed by group representation theory, and even simple geometric considerations. This article presents a purely algebraic approach to RUM identification wherein the conditions of connectedness are used to construct a linear system of equations in the rotational symmetry-mode amplitudes.
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Affiliation(s)
- Branton Campbell
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
| | - Christopher J Howard
- School of Engineering, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia
| | - Tyler B Averett
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
| | - Thomas A Whittle
- School of Chemistry, The University of Sydney, Sydney, NSW 2308, Australia
| | - Siegbert Schmid
- School of Chemistry, The University of Sydney, Sydney, NSW 2308, Australia
| | - Shae Machlus
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
| | - Christopher Yost
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
| | - Harold T Stokes
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
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33
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Phillips AE. Rigid units revisited. Acta Crystallogr A Found Adv 2018; 74:406-407. [PMID: 30182929 DOI: 10.1107/s2053273318012007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 08/24/2018] [Indexed: 11/10/2022] Open
Affiliation(s)
- Anthony E Phillips
- School of Physics and Astronomy, Queen Mary University of London, London E1 4NS, UK
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34
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Porer M, Fechner M, Bothschafter EM, Rettig L, Savoini M, Esposito V, Rittmann J, Kubli M, Neugebauer MJ, Abreu E, Kubacka T, Huber T, Lantz G, Parchenko S, Grübel S, Paarmann A, Noack J, Beaud P, Ingold G, Aschauer U, Johnson SL, Staub U. Ultrafast Relaxation Dynamics of the Antiferrodistortive Phase in Ca Doped SrTiO_{3}. PHYSICAL REVIEW LETTERS 2018; 121:055701. [PMID: 30118273 DOI: 10.1103/physrevlett.121.055701] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Indexed: 06/08/2023]
Abstract
The ultrafast dynamics of the octahedral rotation in Ca:SrTiO_{3} is studied by time-resolved x-ray diffraction after photoexcitation over the band gap. By monitoring the diffraction intensity of a superlattice reflection that is directly related to the structural order parameter of the soft-mode driven antiferrodistortive phase in Ca:SrTiO_{3}, we observe an ultrafast relaxation on a 0.2 ps timescale of the rotation of the oxygen octahedron, which is found to be independent of the initial temperature despite large changes in the corresponding soft-mode frequency. A further, much smaller reduction on a slower picosecond timescale is attributed to thermal effects. Time-dependent density-functional-theory calculations show that the fast response can be ascribed to an ultrafast displacive modification of the soft-mode potential towards the normal state induced by holes created in the oxygen 2p states.
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Affiliation(s)
- M Porer
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
| | - M Fechner
- Max Planck Institute for the Structure and Dynamics of Matter, CFEL, 22761 Hamburg, Germany
- Materials Theory, ETH Zürich, 8093 Zürich, Switzerland
| | - E M Bothschafter
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
| | - L Rettig
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
- Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, 14195 Berlin, Germany
| | - M Savoini
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
| | - V Esposito
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
| | - J Rittmann
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
| | - M Kubli
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
| | - M J Neugebauer
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
| | - E Abreu
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
| | - T Kubacka
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
| | - T Huber
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
| | - G Lantz
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
| | - S Parchenko
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
| | - S Grübel
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
| | - A Paarmann
- Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, 14195 Berlin, Germany
| | - J Noack
- Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society, 14195 Berlin, Germany
| | - P Beaud
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
| | - G Ingold
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
| | - U Aschauer
- Department of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland
| | - S L Johnson
- Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland
| | - U Staub
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
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35
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Elastic and dynamical structural properties of La and Mn-doped SrTiO 3 studied by neutron scattering and their relation with thermal conductivities. Sci Rep 2018; 8:9651. [PMID: 29941897 PMCID: PMC6018226 DOI: 10.1038/s41598-018-27984-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 06/11/2018] [Indexed: 11/08/2022] Open
Abstract
The electron-doped SrTiO3 exhibits good thermoelectric properties, which makes this material a promising candidate of an n-type oxide thermoelectric device. Recent studies indicated that only a few percent co-doping of La and Mn in SrTiO3 substantially reduces the thermal conductivity, thereby greatly improving the thermoelectric figure of merit at room temperature. Our time-of-flight neutron scattering studies revealed that by doping both La and Mn into SrTiO3, the inelastic scattering spectrum shows a momentum-independent increase in the low-energy spectral weight approximately below 10 meV. The increase in the low-energy spectral weight exhibits a clear correlation with thermal conductivity. The correlation is attributed to dynamical and local structural fluctuations caused by the Jahn-Teller instability in Mn3+ ions coupled with the incipient ferroelectric nature of SrTiO3, as the origin of the low thermal conductivity.
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36
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Ye F, Liu Y, Whitfield R, Osborn R, Rosenkranz S. Implementation of cross correlation for energy discrimination on the time-of-flight spectrometer CORELLI. J Appl Crystallogr 2018; 51:315-322. [PMID: 29657565 PMCID: PMC5884386 DOI: 10.1107/s160057671800403x] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 03/08/2018] [Indexed: 11/22/2022] Open
Abstract
The CORELLI instrument at Oak Ridge National Laboratory is a statistical chopper spectrometer designed and optimized to probe complex disorder in crystalline materials through diffuse scattering experiments. On CORELLI, the high efficiency of white-beam Laue diffraction combined with elastic discrimination have enabled an unprecedented data collection rate to obtain both the total and the elastic-only scattering over a large volume of reciprocal space from a single measurement. To achieve this, CORELLI is equipped with a statistical chopper to modulate the incoming neutron beam quasi-randomly, and then the cross-correlation method is applied to reconstruct the elastic component from the scattering data. Details of the implementation of the cross-correlation method on CORELLI are given and its performance is discussed.
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Affiliation(s)
- Feng Ye
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| | - Yaohua Liu
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| | - Ross Whitfield
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| | - Ray Osborn
- Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Stephan Rosenkranz
- Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
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37
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Martelli V, Jiménez JL, Continentino M, Baggio-Saitovitch E, Behnia K. Thermal Transport and Phonon Hydrodynamics in Strontium Titanate. PHYSICAL REVIEW LETTERS 2018; 120:125901. [PMID: 29694090 DOI: 10.1103/physrevlett.120.125901] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Indexed: 05/02/2023]
Abstract
We present a study of thermal conductivity, κ, in undoped and doped strontium titanate in a wide temperature range (2-400 K) and detecting different regimes of heat flow. In undoped SrTiO_{3}, κ evolves faster than cubic with temperature below its peak and in a narrow temperature window. Such behavior, previously observed in a handful of solids, has been attributed to a Poiseuille flow of phonons, expected to arise when momentum-conserving scattering events outweigh momentum-degrading ones. The effect disappears in the presence of dopants. In SrTi_{1-x}Nb_{x}O_{3}, a significant reduction in lattice thermal conductivity starts below the temperature at which the average inter-dopant distance and the thermal wavelength of acoustic phonons become comparable. In the high-temperature regime, thermal diffusivity becomes proportional to the inverse of temperature, with a prefactor set by sound velocity and Planckian time (τ_{p}=(ℏ/k_{B}T)).
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Affiliation(s)
- Valentina Martelli
- Centro Brasileiro de Pesquisas Físicas, 22290-180 Rio de Janeiro, Rio de Janeiro, Brazil
| | - Julio Larrea Jiménez
- Institute of Physics, University of São Paulo, CEP 05508-090 São Paulo, São Paulo, Brazil
| | - Mucio Continentino
- Centro Brasileiro de Pesquisas Físicas, 22290-180 Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Kamran Behnia
- Laboratoire Physique et Etude de Matériaux (CNRS-UPMC), ESPCI Paris, PSL Research University, 75005 Paris, France
- II. Physikalisches Institut, Universität zu Köln, 50937 Köln, Germany
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38
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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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Wang X, Zhang M, Tian X, Zhang Y, Gong J, Rahman A, Dai R, Wang Z, Zhang Z. Strain-induced conductivity accelerated recoveries in LaAlO 3/SrTiO 3 heterostructure with millimeter scale. RSC Adv 2018; 8:37804-37810. [PMID: 35558592 PMCID: PMC9089444 DOI: 10.1039/c8ra08564a] [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: 10/16/2018] [Accepted: 11/05/2018] [Indexed: 11/21/2022] Open
Abstract
The transport and magnetic properties of LaAlO3/SrTiO3 (LAO/STO) heterostructure have been studied during cooling and warming. The strain gradient perpendicular to the surface of the heterostructure increases with the thickness of LAO film. The conductivity accelerated recoveries (CAR) are found at 80 K and 176 K in the interface of LAO/STO sample with millimeter scale, and are more obvious for thicker LAO layers during warming. These two recovering temperatures correspond to the migrating energies of oxygen single vacancy and divacancy trapped by polarized domain walls, separately. This indicated that domain walls diffuse along the longitudinal direction and expand to larger area due the strain gradient perpendicular to the interface. The stable and precise accelerating recovering temperatures make the sample at a larger scale a potential widely applied temperature standard reference. The magnetization measurements reveal the coexistence of paramagnetic and diamagnetic in the LAO/STO samples at whole temperature from 2 K to 300 K. The abnormal electric resistance rise is observed with the decreasing temperature below 25 K for the samples of 7 and 15 LAO layers. This anomaly is attributed to the Kondo effect below 25 K and weak anti-localization below 5 K due to the weightier paramagnetic content. The larger diamagnetic content suppresses these contributions in 25 LAO layers sample. This work provided an insightful view that the strain modified structure domain leads to the enhancement of CAR effect, which helps to achieve a better understanding of domain related physics in the LAO/STO system. The transport and magnetic properties of LaAlO3/SrTiO3 (LAO/STO) heterostructure have been studied during cooling and warming.![]()
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Affiliation(s)
- Xiangqi Wang
- Department of Physics
- University of Science and Technology of China
- Hefei 230026
- China
| | - Min Zhang
- Department of Physics
- University of Science and Technology of China
- Hefei 230026
- China
| | - Xirui Tian
- Department of Physics
- University of Science and Technology of China
- Hefei 230026
- China
| | - Yinying Zhang
- Department of Physics
- University of Science and Technology of China
- Hefei 230026
- China
| | - Junbo Gong
- Department of Physics
- University of Science and Technology of China
- Hefei 230026
- China
| | - Azizur Rahman
- Department of Physics
- University of Science and Technology of China
- Hefei 230026
- China
| | - Rucheng Dai
- The Centre for Physical Experiments
- University of Science and Technology of China
- Hefei 230026
- China
| | - Zhongping Wang
- The Centre for Physical Experiments
- University of Science and Technology of China
- Hefei 230026
- China
| | - Zengming Zhang
- The Centre for Physical Experiments
- University of Science and Technology of China
- Hefei 230026
- China
- Key Laboratory of Strongly-Coupled Quantum Matter Physics
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40
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Schütz P, Di Sante D, Dudy L, Gabel J, Stübinger M, Kamp M, Huang Y, Capone M, Husanu MA, Strocov VN, Sangiovanni G, Sing M, Claessen R. Dimensionality-Driven Metal-Insulator Transition in Spin-Orbit-Coupled SrIrO_{3}. PHYSICAL REVIEW LETTERS 2017; 119:256404. [PMID: 29303315 DOI: 10.1103/physrevlett.119.256404] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Indexed: 05/27/2023]
Abstract
Upon reduction of the film thickness we observe a metal-insulator transition in epitaxially stabilized, spin-orbit-coupled SrIrO_{3} ultrathin films. By comparison of the experimental electronic dispersions with density functional theory at various levels of complexity we identify the leading microscopic mechanisms, i.e., a dimensionality-induced readjustment of octahedral rotations, magnetism, and electronic correlations. The astonishing resemblance of the band structure in the two-dimensional limit to that of bulk Sr_{2}IrO_{4} opens new avenues to unconventional superconductivity by "clean" electron doping through electric field gating.
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Affiliation(s)
- P Schütz
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - D Di Sante
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - L Dudy
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - J Gabel
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - M Stübinger
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - M Kamp
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Y Huang
- Van der Waals-Zeeman Insitute, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - M Capone
- CNR-IOM-Democritos National Simulation Centre and International School for Advanced Studies (SISSA), Via Bonomea 265, I-34136 Trieste, Italy
| | - M-A Husanu
- National Institute of Materials Physics, Atomistilor 405 A, 077125 Magurele, Romania
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - G Sangiovanni
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - M Sing
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - R Claessen
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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41
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Dai W, Yang M, Lee H, Lee JW, Eom CB, Cen C. Tailoring the Doping Mechanisms at Oxide Interfaces in Nanoscale. NANO LETTERS 2017; 17:5620-5625. [PMID: 28806520 DOI: 10.1021/acs.nanolett.7b02508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Here, we demonstrate the nanoscale manipulations of two types of charge transfer to the LaAlO3/SrTiO3 interfaces: one from surface adsorbates and another from oxygen vacancies inside LaAlO3 films. This method can be used to produce multiple insulating and metallic interface states with distinct carrier properties that are highly stable in air. By reconfiguring the patterning and comparing interface structures formed from different doping sources, effects of extrinsic and intrinsic material characters on the transport properties can be distinguished. In particular, a multisubband to single-subband transition controlled by the structural phases in SrTiO3 was revealed. In addition, the transient behaviors of nanostructures also provided a unique opportunity to study the nanoscale diffusions of adsorbates and oxygen vacancies in oxide heterostructures. Knowledge of such dynamic processes is important for nanodevice implementations.
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Affiliation(s)
- Weitao Dai
- Department of Physics and Astronomy, West Virginia University , Morgantown, West Virginia 26506, United States
| | - Ming Yang
- Department of Physics and Astronomy, West Virginia University , Morgantown, West Virginia 26506, United States
| | - Hyungwoo Lee
- Department of Material Science and Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
| | - Jung-Woo Lee
- Department of Material Science and Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
| | - Chang-Beom Eom
- Department of Material Science and Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
| | - Cheng Cen
- Department of Physics and Astronomy, West Virginia University , Morgantown, West Virginia 26506, United States
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42
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Maniv E, Dagan Y, Goldstein M. Correlation-Induced Band Competition in SrTiO3/LaAlO3. ACTA ACUST UNITED AC 2017. [DOI: 10.1557/adv.2017.92] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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43
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Canu G, Buscaglia V. Hydrothermal synthesis of strontium titanate: thermodynamic considerations, morphology control and crystallisation mechanisms. CrystEngComm 2017. [DOI: 10.1039/c7ce00834a] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The hydrothermal/solvothermal method is one of the most versatile synthetic routes for producing a large number of compounds. The thermodynamic aspects, the control of morphology and the crystallisation mechanisms are reviewed and discussed in this highlight, with special emphasis on the synthesis of SrTiO3, as a model system.
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Affiliation(s)
- Giovanna Canu
- Institute of Condensed Matter Chemistry and Technologies for Energy
- National Research Council
- I-16149 Genoa
- Italy
| | - Vincenzo Buscaglia
- Institute of Condensed Matter Chemistry and Technologies for Energy
- National Research Council
- I-16149 Genoa
- Italy
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44
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Schubert M. Coordinate-Invariant Lyddane-Sachs-Teller Relationship for Polar Vibrations in Materials with Monoclinic and Triclinic Crystal Systems. PHYSICAL REVIEW LETTERS 2016; 117:215502. [PMID: 27911546 DOI: 10.1103/physrevlett.117.215502] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Indexed: 06/06/2023]
Abstract
A coordinate-invariant generalization of the Lyddane-Sachs-Teller relation is presented for polar vibrations in materials with monoclinic and triclinic crystal systems. The generalization is derived from an eigendielectric displacement vector summation approach, which is equivalent to the microscopic Born-Huang description of polar lattice vibrations in the harmonic approximation. An expression for a general oscillator strength is also described for materials with monoclinic and triclinic crystal systems. A generalized factorized form of the dielectric response characteristic for monoclinic and triclinic materials is proposed. The generalized Lyddane-Sachs-Teller relation is found valid for monoclinic β-Ga_{2}O_{3}, where accurate experimental data became available recently from a comprehensive generalized ellipsometry investigation [Phys. Rev. B 93, 125209 (2016)]. Data for triclinic crystal systems can be measured by generalized ellipsometry as well, and are anticipated to become available soon and results can be compared with the generalized relations presented here.
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Affiliation(s)
- Mathias Schubert
- Department of Electrical and Computer Engineering and Center for Nanohybrid Functional Materials, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA
- Leibniz Institute for Polymer Research, 01069 Dresden, Germany
- Department of Physics, Chemistry, and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
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45
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Zhang B, Wu L, Yin WG, Sun CJ, Yang P, Venkatesan T, Chen J, Zhu Y, Chow GM. Interfacial Coupling-Induced Ferromagnetic Insulator Phase in Manganite Film. NANO LETTERS 2016; 16:4174-4180. [PMID: 27276032 DOI: 10.1021/acs.nanolett.6b01056] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Interfaces with subtle differences in atomic and electronic structures in perovskite ABO3 heterostructures often yield intriguingly different properties, yet their exact roles remain elusive. Here, we report an integrated study of unusual transport, magnetic, and structural properties of Pr0.67Sr0.33MnO3 film on SrTiO3 substrate. The variations in the out-of-plane lattice constant and BO6 octahedral rotation across the Pr0.67Sr0.33MnO3/SrTiO3 interface strongly depend on the thickness of the Pr0.67Sr0.33MnO3 film. In the 12 nm film, a new interface-sensitive ferromagnetic polaronic insulator (FI') phase is formed during the cubic-to-tetragonal phase transition of SrTiO3, apparently due to the enhanced electron-phonon interaction and atomic disorder in the film. The transport properties of the FI' phase in the 30 nm film are masked because of the reduced interfacial coupling and smaller interface-to-volume ratio. This work demonstrates how thickness-dependent interfacial coupling leads to the formation of a theoretically predicted ferromagnetic-polaronic insulator, as illustrated in a new phase diagram, that is otherwise ferromagnetic metal (FM) in bulk form.
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Affiliation(s)
- Bangmin Zhang
- Department of Materials Science & Engineering, National University of Singapore , 117576, Singapore
| | - Lijun Wu
- Condensed Matter Physics & Materials Science Division, Brookhaven National Laboratory , Upton, New York 11973, United States
| | - Wei-Guo Yin
- Condensed Matter Physics & Materials Science Division, Brookhaven National Laboratory , Upton, New York 11973, United States
| | - Cheng-Jun Sun
- Advanced Photon Source, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Ping Yang
- Singapore Synchrotron Light Source (SSLS), National University of Singapore , 5 Research Link, 117603 Singapore
| | - T Venkatesan
- NUSNNI-Nanocore, National University of Singapore , 117411, Singapore
- Department of Physics, National University of Singapore , 117542, Singapore
- Department of Electrical & Computer Engineering, National University of Singapore , 117576, Singapore
| | - Jingsheng Chen
- Department of Materials Science & Engineering, National University of Singapore , 117576, Singapore
| | - Yimei Zhu
- Condensed Matter Physics & Materials Science Division, Brookhaven National Laboratory , Upton, New York 11973, United States
| | - Gan Moog Chow
- Department of Materials Science & Engineering, National University of Singapore , 117576, Singapore
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46
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Manaka H, Yagi G, Miura Y. Development of birefringence imaging analysis method for observing cubic crystals in various phase transitions. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:073704. [PMID: 27475562 DOI: 10.1063/1.4958662] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Optical birefringence imaging systems demonstrate a high potential for comprehensively investigating various phase transitions. To completely demonstrate such abilities, the temperature dependence of birefringence (Δn) was measured in Δn ≃ 0 materials (i.e., cubic crystals with imperfect crystallization) via a background subtraction method. As a result, highly accurate birefringence imaging at 384 × 288 pixels was obtained using phase transition processes as well as varying temperatures visually characterized by the spatial distribution of not only the retardance level but also the optical fast-axis azimuth.
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Affiliation(s)
- Hirotaka Manaka
- Graduate School of Science and Engineering, Kagoshima University, Korimoto, Kagoshima 890-0065, Japan
| | - Genta Yagi
- Graduate School of Science and Engineering, Kagoshima University, Korimoto, Kagoshima 890-0065, Japan
| | - Yoko Miura
- National Institute of Technology, Suzuka College, Shiroko-cho, Suzuka, Mie 510-0294, Japan
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47
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Dove MT, Fang H. Negative thermal expansion and associated anomalous physical properties: review of the lattice dynamics theoretical foundation. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2016; 79:066503. [PMID: 27177210 DOI: 10.1088/0034-4885/79/6/066503] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Negative thermal expansion (NTE) is the phenomenon in which materials shrink rather than expand on heating. Although NTE had been previously observed in a few simple materials at low temperature, it was the realisation in 1996 that some materials have NTE over very wide ranges of temperature that kick-started current interest in this phenomenon. Now, nearly two decades later, a number of families of ceramic NTE materials have been identified. Increasingly quantitative studies focus on the mechanism of NTE, through techniques such as high-pressure diffraction, local structure probes, inelastic neutron scattering and atomistic simulation. In this paper we review our understanding of vibrational mechanisms of NTE for a range of materials. We identify a number of different cases, some of which involve a small number of phonons that can be described as involving rotations of rigid polyhedral groups of atoms, others where there are large bands of phonons involved, and some where the transverse acoustic modes provide the main contribution to NTE. In a few cases the elasticity of NTE materials has been studied under pressure, identifying an elastic softening under pressure. We propose that this property, called pressure-induced softening, is closely linked to NTE, which we can demonstrate using a simple model to describe NTE materials. There has also been recent interest in the role of intrinsic anharmonic interactions on NTE, particularly guided by calculations of the potential energy wells for relevant phonons. We review these effects, and show how anhamonicity affects the response of the properties of NTE materials to pressure.
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Affiliation(s)
- Martin T Dove
- School of Physics and Astronomy, and Materials Research Institute, Queen Mary University of London, Mile End Road, London E1 4NS, UK
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48
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Abstract
Phase transitions in ABX3 perovskites are often accompanied by rigid rotations of the corner-connected BX6 octahedral network. Although the mechanisms for the preferred rotation patterns of perovskite oxides are fairly well recognized, the same cannot be said of halide variants (i.e., X = Cl, Br, or I), several of which undergo an unusual displacive transition to a tetragonal phase exhibiting in-phase rotations about one axis (a(0)a(0)c(+) in Glazer notation). To discern the chemical factors stabilizing this unique phase, we investigated a series of 12 perovskite bromides and iodides using density functional theory calculations and compared them with similar oxides. We find that in-phase tilting provides a better arrangement of the larger bromide and iodide anions, which minimizes the electrostatic interactions, improves the bond valence of the A-site cations, and enhances the covalency between the A-site metal and Br(-) or I(-) ions. The opposite effect is present in the oxides, with out-of-phase tilting maximizing these factors.
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Affiliation(s)
- Joshua Young
- Department of Materials Science and Engineering, Drexel University , Philadelphia, Pennsylvania 19104, United States
| | - James M Rondinelli
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
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49
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Gregori G, Köhler J, Scott JF, Bussmann-Holder A. Hidden magnetism in the paramagnetic phase of EuTiO₃. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:496003. [PMID: 26596645 DOI: 10.1088/0953-8984/27/49/496003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
EuTiO3 is investigated experimentally by temperature dependent conductivity and dielectric constant measurements. Both data sets evidence a crossover behavior in their temperature dependence around T * ~ 200 K indicating a change of the electrical and magnetic behavior of EuTiO3 as already observed by muon spin rotation (μSR) measurements. Around T ' = 80 K an additional anomaly appears which is consistent with previous resonant ultrasound spectroscopy (RUS) data. By applying a magnetic field (1.2 T at room temperature) the bulk conductivity is anomalously enhanced by more than one order of magnitude. The bulk dielectric constant ε(r) decreases with increasing temperature and is enhanced by the magnetic field by up to 22%. All data reveal a substantial hysteresis which is diminished in a magnetic field. The unusual magnetic field dependence of all quantities is suggested to stem from magnetically active domain walls which are mobile between the structural phase transition temperature (T(S) = 282 K) and T * and are pinned below it.
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Affiliation(s)
- G Gregori
- Max Planck Institute for Solid State Research, Heisenbergstr.1, D-70569 Stuttgart, Germany
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50
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Edge JM, Kedem Y, Aschauer U, Spaldin NA, Balatsky AV. Quantum Critical Origin of the Superconducting Dome in SrTiO_{3}. PHYSICAL REVIEW LETTERS 2015; 115:247002. [PMID: 26705650 DOI: 10.1103/physrevlett.115.247002] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Indexed: 06/05/2023]
Abstract
We expand the well-known notion that quantum criticality can induce superconductivity by proposing a concrete mechanism for superconductivity due to quantum ferroelectric fluctuations. To this end, we investigate the origin of superconductivity in doped SrTiO_{3} using a combination of density functional and strong coupling theories within the framework of quantum criticality. Our density functional calculations of the ferroelectric soft mode frequency as a function of doping reveal a crossover related to quantum paraelectricity at a doping level coincident with the experimentally observed top of the superconducting dome. Thus, we suggest a model in which the soft mode fluctuations provide the pairing interaction for superconductivity carriers. Within our model, the low doping limit of the superconducting dome is explained by the emergence of the Fermi surface, and the high doping limit by departure from the quantum critical regime. We predict that the highest critical temperature will increase and shift to lower carrier doping with increasing ^{18}O isotope substitution, a scenario that is experimentally verifiable. Our model is applicable to other quantum paraelectrics, such as KTaO_{3}.
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Affiliation(s)
- Jonathan M Edge
- Nordita, Center for Quantum Materials, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, 10691 Stockholm, Sweden
| | - Yaron Kedem
- Nordita, Center for Quantum Materials, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, 10691 Stockholm, Sweden
| | - Ulrich Aschauer
- Materials Theory, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zürich, Switzerland
| | - Nicola A Spaldin
- Materials Theory, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zürich, Switzerland
| | - Alexander V Balatsky
- Nordita, Center for Quantum Materials, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, 10691 Stockholm, Sweden
- Institute for Materials Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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