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Pascale F, Gueddida S, Doll K, Dovesi R. Band gap, Jahn-Teller deformation, octahedra rotation in transition metal perovskites LaTiO 3 . J Comput Chem 2024; 45:683-694. [PMID: 38095335 DOI: 10.1002/jcc.27274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 11/15/2023] [Accepted: 11/17/2023] [Indexed: 03/02/2024]
Abstract
The LaTiO3 perovskite (where Ti is in a d1 state) is investigated by using an all electron Gaussian basis and many functionals, ranging from pure GGA (PBE), to hybrids (full range, B3LYP and PBE0, and range separated, HSE06) to Hartree Fock. Recently, Varignon et al. (Phys. Rev. Res 1, 033131, 2019), showed that, when GGA+U or HSE06 are used, a metallic solution and fractional occupancy of the t2 g subshell are obtained. Here, it is shown that when a full range hybrid functional is used, an integer occupancy is obtained, as suggested by the Jahn-Teller theorem. When the exact exchange percentage varies from 0 to 100, the system is insulating when it exceeds 20. By reducing progressively the symmetry from cubic down to orthorhombic, the relative importance of the Jahn-Teller deformation and of the rotation of the octahedra is explored.
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Affiliation(s)
- F Pascale
- Université de Lorraine-Nancy, CNRS, LEMTA, Nancy, France
| | - S Gueddida
- Université de Lorraine-Nancy, CNRS, LPCT, UMR, Vandoeuvre-lés-Nancy, France
| | - K Doll
- University of Stuttgart, Molpro Quantum Chemistry Software, Institute of Theoretical Chemistry, Stuttgart, Germany
| | - R Dovesi
- Accademia Delle Science di Torino, Torinoto, Italy
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Cao G, Weng Y, Yao X, Ward TZ, Gai Z, Mandrus D, Dong S. Effect of Mn doping and charge transfer on LaTi 1-xMn xO 3. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 35:055601. [PMID: 36410040 DOI: 10.1088/1361-648x/aca4b3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Accepted: 11/21/2022] [Indexed: 06/16/2023]
Abstract
We report the magnetic and electronic transport properties of Mn-doped LaTi1-xMnxO3(x= 0, 0.1, 0.3, 0.5) as a function of temperature and an applied magnetic field. It was found that the Mn-doped samples show a magnetic transition which is not present in the parent LaTiO3. The Mn-doped samples showed fluctuations in magnetization at low fields below their Néel transition temperature indicating electronic phase separation in the material. Increased Mn content in the sample strengthens the ferromagnetic-like moment while maintaining G-type antiferromagnetic phase by charge transfer from Mn to Ti and influencing orbital ordering of the Ti3+t2gorbitals. The results are discussed in parallel with transport and bulk magnetization measurements detailing the electronic behavior. An additional context for the mechanism is supported by first-principles density-function theory calculations.
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Affiliation(s)
- Guixin Cao
- Materials Genome Institute, Shanghai University, Shanghai 200444, People's Republic of China
| | - Yakui Weng
- School of Science, Nanjing University of Posts and Telecommunications, Nanjing 210023, People's Republic of China
| | - Xinyu Yao
- Materials Genome Institute, Shanghai University, Shanghai 200444, People's Republic of China
| | - T Zac Ward
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States of America
| | - Zheng Gai
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37830, United States of America
| | - David Mandrus
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States of America
| | - Shuai Dong
- School of Physics, Southeast University, Nanjing 211189, People's Republic of China
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Chang YJ, Phark SH. Direct Nanoscale Analysis of Temperature-Resolved Growth Behaviors of Ultrathin Perovskites on SrTiO3. ACS NANO 2016; 10:5383-90. [PMID: 27163291 DOI: 10.1021/acsnano.6b01592] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Revealing growth mechanism of a thin film and properties of its film-substrate interface necessarily require microscopic investigations on the initial growth stages in temperature- and thickness-resolved manners. Here we applied in situ scanning tunneling microscopy and atomic force microscopy to investigate the growth dynamics in homo- (SrTiO3) and hetero- (SrRuO3) epitaxies on SrTiO3(001). A comparison of temperature-dependent surface structures of SrRuO3 and SrTiO3 films suggests that the peculiar growth mode switching from a "layer-by-layer" to "step-flow" type in a SrRuO3 films arises from a reduction of surface migration barrier, caused by the change in the chemical configuration of the interface between the topmost and underlying layers. Island densities in perovskite epitaxies exhibited a clear linear inverse-temperature dependence. A prototypical study on island nucleation stage of SrTiO3 homoepitaxy revealed that classical diffusion model is valid for the perovskite growths.
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Affiliation(s)
- Young Jun Chang
- Department of Physics, University of Seoul , Seoul 02504, Korea
| | - Soo-Hyon Phark
- Center for Correlated Electron Systems, Institute for Basic Science , Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University , Seoul 08826, Korea
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Jeong DW, Choi WS, Okamoto S, Kim JY, Kim KW, Moon SJ, Cho DY, Lee HN, Noh TW. Dimensionality control of d-orbital occupation in oxide superlattices. Sci Rep 2014; 4:6124. [PMID: 25134975 PMCID: PMC4137265 DOI: 10.1038/srep06124] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 07/30/2014] [Indexed: 12/04/2022] Open
Abstract
Manipulating the orbital state in a strongly correlated electron system is of fundamental and technological importance for exploring and developing novel electronic phases. Here, we report an unambiguous demonstration of orbital occupancy control between t2g and eg multiplets in quasi-two-dimensional transition metal oxide superlattices (SLs) composed of a Mott insulator LaCoO3 and a band insulator LaAlO3. As the LaCoO3 sublayer thickness approaches its fundamental limit (i.e. one unit-cell-thick), the electronic state of the SLs changed from a Mott insulator, in which both t2g and eg orbitals are partially filled, to a band insulator by completely filling (emptying) the t2g (eg) orbitals. We found the reduction of dimensionality has a profound effect on the electronic structure evolution, which is, whereas, insensitive to the epitaxial strain. The remarkable orbital controllability shown here offers a promising pathway for novel applications such as catalysis and photovoltaics, where the energy of d level is an essential parameter.
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Affiliation(s)
- Da Woon Jeong
- 1] Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-747, Korea [2] Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
| | - Woo Seok Choi
- 1] Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States [2] Department of Physics, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746, Korea
| | - Satoshi Okamoto
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Jae-Young Kim
- Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Kyung Wan Kim
- Department of Physics, Chungbuk National University, Cheongju 361-763, Korea
| | - Soon Jae Moon
- Department of Physics, Hanyang University, Seoul 133-791, Korea
| | - Deok-Yong Cho
- 1] Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-747, Korea [2] Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea [3] Department of Physics, Chonbuk National University, Jeonju 561-756, Korea
| | - Ho Nyung Lee
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Tae Won Noh
- 1] Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-747, Korea [2] Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
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Park J, Cho BG, Kim KD, Koo J, Jang H, Ko KT, Park JH, Lee KB, Kim JY, Lee DR, Burns CA, Seo SSA, Lee HN. Oxygen-vacancy-induced orbital reconstruction of Ti ions at the interface of LaAlO3/SrTiO3 heterostructures: a resonant soft-X-ray scattering study. PHYSICAL REVIEW LETTERS 2013; 110:017401. [PMID: 23383835 DOI: 10.1103/physrevlett.110.017401] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Indexed: 06/01/2023]
Abstract
Resonant soft-x-ray scattering measurements have been performed to investigate interface electronic structures of (LaAlO(3)/SrTiO(3)) superlattices. Resonant scattering intensities at superlattice reflections show clear evidence of degeneracy lifting in t(2g) states of interface Ti ions. Polarization dependence of intensities indicates the energy of d(xy) states is lower by ~1 eV than two other t(2g) states. The energy splitting is insensitive to epitaxial strain. The orbital reconstruction is induced by oxygen vacancies and confined to the interface within two unit cells, indicating charge compensation at the polar interfaces.
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Affiliation(s)
- J Park
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
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Liu J, Kareev M, Meyers D, Gray B, Ryan P, Freeland JW, Chakhalian J. Metal-insulator transition and orbital reconstruction in Mott-type quantum wells made of NdNiO3. PHYSICAL REVIEW LETTERS 2012; 109:107402. [PMID: 23005325 DOI: 10.1103/physrevlett.109.107402] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2011] [Indexed: 05/27/2023]
Abstract
The metal-insulator transition and the underlying electronic and orbital structure in e(g)(1) quantum wells based on NdNiO3 were investigated by dc transport and resonant soft x-ray absorption spectroscopy. By comparing quantum wells of the same dimension but with two different confinement structures, we explicitly demonstrate that the quantum well boundary condition of correlated electrons is critical to selecting the many-body ground state. In particular, the long-range orderings and the metal-insulator transition are found to be strongly enhanced under quantum confinement by sandwiching NdNiO(3) with the wide-gap dielectric LaAlO(3), while they are suppressed when one of the interfaces is replaced by a surface (interface with vacuum). Resonant spectroscopy reveals that the reduced charge fluctuations in the sandwich structure are supported by the enhanced propensity to charge ordering due to the suppressed e(g) orbital splitting when interfaced with the confining LaAlO3 layer.
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Affiliation(s)
- Jian Liu
- Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA.
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Hwang HY, Iwasa Y, Kawasaki M, Keimer B, Nagaosa N, Tokura Y. Emergent phenomena at oxide interfaces. NATURE MATERIALS 2012; 11:103-13. [PMID: 22270825 DOI: 10.1038/nmat3223] [Citation(s) in RCA: 725] [Impact Index Per Article: 60.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Recent technical advances in the atomic-scale synthesis of oxide heterostructures have provided a fertile new ground for creating novel states at their interfaces. Different symmetry constraints can be used to design structures exhibiting phenomena not found in the bulk constituents. A characteristic feature is the reconstruction of the charge, spin and orbital states at interfaces on the nanometre scale. Examples such as interface superconductivity, magneto-electric coupling, and the quantum Hall effect in oxide heterostructures are representative of the scientific and technological opportunities in this rapidly emerging field.
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Affiliation(s)
- H Y Hwang
- Correlated Electron Research Group, RIKEN-Advanced Science Institute, Saitama 351-0198, Japan.
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Delugas P, Filippetti A, Fiorentini V, Bilc DI, Fontaine D, Ghosez P. Spontaneous 2-dimensional carrier confinement at the n-type SrTiO3/LaAlO3 interface. PHYSICAL REVIEW LETTERS 2011; 106:166807. [PMID: 21599400 DOI: 10.1103/physrevlett.106.166807] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Indexed: 05/30/2023]
Abstract
We describe the intrinsic mechanism of 2-dimensional electron confinement at the n-type SrTiO3/LaAlO3 interface as a function of the sheet carrier density n(s) via advanced first-principles calculations. Electrons localize spontaneously in Ti 3d(xy) levels within a thin (≲2 nm) interface-adjacent SrTiO3 region for n(s) lower than a threshold value n(c)∼10(14) cm(-2). For n(s)>n(c) a portion of charge flows into Ti 3d(xz)-d(yz) levels extending farther from the interface. This intrinsic confinement can be attributed to the interface-induced symmetry breaking and localized nature of Ti 3d t(2g) states. The sheet carrier density directly controls the binding energy and the spatial extension of the conductive region. A direct, quantitative relation of these quantities with n(s) is provided.
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Affiliation(s)
- Pietro Delugas
- CNR-IOM UOS Cagliari, Dipartimento di Fisica, Università di Cagliari, Monserrato (CA), Italy
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