1
|
Xia C, Chen Y, Chen H. Pressure-induced metal-insulator transition in oxygen-deficient LiNbO 3-type ferroelectrics. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 34:025501. [PMID: 34624871 DOI: 10.1088/1361-648x/ac2e30] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 10/08/2021] [Indexed: 06/13/2023]
Abstract
Hydrostatic pressure and oxygen vacancies usually have deleterious effects on ferroelectric materials because both tend to reduce their polarization. In this work we use first-principles calculations to study an important class of ferroelectric materials-LiNbO3-type ferroelectrics (LiNbO3as the prototype), and find that in oxygen-deficient LiNbO3-δ, hydrostatic pressure induces an unexpected metal-insulator transition between 8 and 9 GPa. Our calculations also find that strong polar displacements persist in both metallic and insulating oxygen-deficient LiNbO3-δand the size of polar displacements is comparable to pristine LiNbO3under the same pressure. These properties are distinct from widely used perovskite ferroelectric oxide BaTiO3, whose polarization is quickly suppressed by hydrostatic pressure and/or oxygen vacancies. The anomalous pressure-driven metal-insulator transition in oxygen-deficient LiNbO3-δarises from the change of an oxygen vacancy defect state. Hydrostatic pressure increases the polar displacements of oxygen-deficient LiNbO3-δ, which reduces the band width of the defect state and eventually turns it into an in-gap state. In the insulating phase, the in-gap state is further pushed away from the conduction band edge under hydrostatic pressure, which increases the fundamental gap. Our work shows that for LiNbO3-type strong ferroelectrics, oxygen vacancies and hydrostatic pressure combined can lead to new phenomena and potential functions, in contrast to the harmful effects occurring to perovskite ferroelectric oxides such as BaTiO3.
Collapse
Affiliation(s)
- Chengliang Xia
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, People's Republic of China
- NYU-ECNU Institute of Physics, NYU Shanghai, Shanghai, 200062, People's Republic of China
| | - Yue Chen
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, People's Republic of China
| | - Hanghui Chen
- NYU-ECNU Institute of Physics, NYU Shanghai, Shanghai, 200062, People's Republic of China
- Department of Physics, New York University, New York 10003, United States of America
| |
Collapse
|
2
|
Yoon S, Jin K, Lee S, Nam KT, Kim M, Kwon YK. Effects of paramagnetic fluctuations on the thermochemistry of MnO(100) surfaces in the oxygen evolution reaction. Phys Chem Chem Phys 2021; 23:859-865. [PMID: 33074274 DOI: 10.1039/d0cp03779f] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We investigated the effects of paramagnetic (PM) fluctuations on the thermochemistry of the MnO(100) surface in the oxygen evolution reaction (OER) using the "noncollinear magnetic sampling method plus U" (NCMSM+U). Various physical properties, such as the electronic structure, free energy, and charge occupation, of the MnO(100) surface in the PM state with several OER intermediates, were reckoned and compared to those in the antiferromagnetic (AFM) state. We found that PM fluctuation enhances charge transfer from a surface Mn ion to each of the intermediates and strengthens the chemical bond between them, while not altering the overall features, such as the rate determining step and resting state, in reaction pathways. The enhanced charge transfer can be attributed to the delocalized nature of valence bands observed in the PM surface. In addition, it was observed that chemical-bond enhancement depends on the intermediates, resulting in significant deviations in reaction energy barriers. Our study suggests that PM fluctuations play a significant role in the thermochemistry of chemical reactions occurring on correlated oxide surfaces.
Collapse
Affiliation(s)
- Sangmoon Yoon
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Korea. and Department of Physics, Kyung Hee University, Seoul, 02447, Korea.
| | - Kyoungsuk Jin
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Korea.
| | - Sangmin Lee
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Korea.
| | - Ki Tae Nam
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Korea.
| | - Miyoung Kim
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Korea.
| | - Young-Kyun Kwon
- Department of Physics, Kyung Hee University, Seoul, 02447, Korea.
| |
Collapse
|
3
|
Wang YC, Jiang H. Local screened Coulomb correction approach to strongly correlated d-electron systems. J Chem Phys 2019; 150:154116. [DOI: 10.1063/1.5089464] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Yue-Chao Wang
- Beijing National Laboratory for Molecular Sciences, Institute of Theoretical and Computational Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Hong Jiang
- Beijing National Laboratory for Molecular Sciences, Institute of Theoretical and Computational Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| |
Collapse
|
4
|
Yoon S, Kang SH, Lee S, Kim K, Song JP, Kim M, Kwon YK. A "non-dynamical" way of describing room-temperature paramagnetic manganese oxide. Phys Chem Chem Phys 2019; 21:15932-15939. [PMID: 31094381 DOI: 10.1039/c9cp00280d] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
We present a new approach based on static density functional theory (DFT) to describe paramagnetic manganese oxides, representative paramagnetic Mott insulators. We appended spin noncollinearity and a canonical ensemble to the magnetic sampling method (MSM), which is one of the supercell approaches based on the disordered local moment model. The combination of the noncollinear MSM (NCMSM) with DFT+U represents a highly favorable computational method called NCMSM+U to accurately determine the paramagnetic properties of MnO with moderate numerical cost. The effects of electron correlations and spin noncollinearity on the properties of MnO were also investigated. We found that the spin noncollinearity plays an important role in determining the detailed electronic profile and precise energetics of paramagnetic MnO. Our results illustrate that the NCMSM+U approach may be used for insulating materials as an alternative to the ab initio framework of dynamic mean field theory based on DFT in the simulation of the room-temperature paramagnetic properties.
Collapse
Affiliation(s)
- Sangmoon Yoon
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Korea.
| | | | | | | | | | | | | |
Collapse
|
5
|
|
6
|
Kim SY, Lee MC, Han G, Kratochvilova M, Yun S, Moon SJ, Sohn C, Park JG, Kim C, Noh TW. Spectroscopic Studies on the Metal-Insulator Transition Mechanism in Correlated Materials. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1704777. [PMID: 29761925 DOI: 10.1002/adma.201704777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 12/18/2017] [Indexed: 06/08/2023]
Abstract
The metal-insulator transition (MIT) in correlated materials is a novel phenomenon that accompanies a large change in resistivity, often many orders of magnitude. It is important in its own right but its switching behavior in resistivity can be useful for device applications. From the material physics point of view, the starting point of the research on the MIT should be to understand the microscopic mechanism. Here, an overview of recent efforts to unravel the microscopic mechanisms for various types of MITs in correlated materials is provided. Research has focused on transition metal oxides (TMOs), but transition metal chalcogenides have also been studied. Along the way, a new class of MIT materials is discovered, the so-called relativistic Mott insulators in 5d TMOs. Distortions in the MO6 (M = transition metal) octahedron are found to have a large and peculiar effect on the band structure in an orbital dependent way, possibly paving a way to the orbital selective Mott transition. In the final section, the character of the materials suitable for applications is summarized, followed by a brief discussion of some of the efforts to control MITs in correlated materials, including a dynamical approach using light.
Collapse
Affiliation(s)
- So Yeun Kim
- 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
| | - Min-Cheol Lee
- 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
| | - Garam Han
- 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
| | - Marie Kratochvilova
- 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
| | - Seokhwan Yun
- 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
| | - Soon Jae Moon
- Department of Physics, Hanyang University, Seoul, Republic of Korea
| | - Changhee Sohn
- Materials Science and Technology Division, Oak Ridge National Laboratory, TN, 37831, USA
| | - Je-Geun Park
- 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
| | - Changyoung Kim
- 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
| | - Tae Won Noh
- 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
| |
Collapse
|
7
|
High Pressure Induced Insulator-to-Semimetal Transition through Intersite Charge Transfer in NaMn7O12. CRYSTALS 2018. [DOI: 10.3390/cryst8020081] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
8
|
Shen G, Mao HK. High-pressure studies with x-rays using diamond anvil cells. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:016101. [PMID: 27873767 DOI: 10.1088/1361-6633/80/1/016101] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Pressure profoundly alters all states of matter. The symbiotic development of ultrahigh-pressure diamond anvil cells, to compress samples to sustainable multi-megabar pressures; and synchrotron x-ray techniques, to probe materials' properties in situ, has enabled the exploration of rich high-pressure (HP) science. In this article, we first introduce the essential concept of diamond anvil cell technology, together with recent developments and its integration with other extreme environments. We then provide an overview of the latest developments in HP synchrotron techniques, their applications, and current problems, followed by a discussion of HP scientific studies using x-rays in the key multidisciplinary fields. These HP studies include: HP x-ray emission spectroscopy, which provides information on the filled electronic states of HP samples; HP x-ray Raman spectroscopy, which probes the HP chemical bonding changes of light elements; HP electronic inelastic x-ray scattering spectroscopy, which accesses high energy electronic phenomena, including electronic band structure, Fermi surface, excitons, plasmons, and their dispersions; HP resonant inelastic x-ray scattering spectroscopy, which probes shallow core excitations, multiplet structures, and spin-resolved electronic structure; HP nuclear resonant x-ray spectroscopy, which provides phonon densities of state and time-resolved Mössbauer information; HP x-ray imaging, which provides information on hierarchical structures, dynamic processes, and internal strains; HP x-ray diffraction, which determines the fundamental structures and densities of single-crystal, polycrystalline, nanocrystalline, and non-crystalline materials; and HP radial x-ray diffraction, which yields deviatoric, elastic and rheological information. Integrating these tools with hydrostatic or uniaxial pressure media, laser and resistive heating, and cryogenic cooling, has enabled investigations of the structural, vibrational, electronic, and magnetic properties of materials over a wide range of pressure-temperature conditions.
Collapse
Affiliation(s)
- Guoyin Shen
- Geophysical Laboratory, Carnegie Institution of Washington, Washington DC, USA
| | | |
Collapse
|
9
|
Timirgazin MA, Igoshev PA, Arzhnikov AK, Yu Irkhin V. Magnetic states, correlation effects and metal-insulator transition in FCC lattice. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:505601. [PMID: 27779131 DOI: 10.1088/0953-8984/28/50/505601] [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
The ground-state magnetic phase diagram (including collinear and spiral states) of the single-band Hubbard model for the face-centered cubic lattice and related metal-insulator transition (MIT) are investigated within the slave-boson approach by Kotliar and Ruckenstein. The correlation-induced electron spectrum narrowing and a comparison with a generalized Hartree-Fock approximation allow one to estimate the strength of correlation effects. This, as well as the MIT scenario, depends dramatically on the ratio of the next-nearest and nearest electron hopping integrals [Formula: see text]. In contrast with metallic state, possessing substantial band narrowing, insulator one is only weakly correlated. The magnetic (Slater) scenario of MIT is found to be superior over the Mott one. Unlike simple and body-centered cubic lattices, MIT is the first order transition (discontinuous) for most [Formula: see text]. The insulator state is type-II or type-III antiferromagnet, and the metallic state is spin-spiral, collinear antiferromagnet or paramagnet depending on [Formula: see text]. The picture of magnetic ordering is compared with that in the standard localized-electron (Heisenberg) model.
Collapse
Affiliation(s)
- M A Timirgazin
- Physical-Technical Institute, Ural Branch of Russian Academy of Sciences-426000 Izhevsk, Russia
| | | | | | | |
Collapse
|
10
|
Salamat A, Fischer RA, Briggs R, McMahon MI, Petitgirard S. In situ synchrotron X-ray diffraction in the laser-heated diamond anvil cell: Melting phenomena and synthesis of new materials. Coord Chem Rev 2014. [DOI: 10.1016/j.ccr.2014.01.034] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
11
|
Li G, Li Y, Zhang M, Ma Y, Ma Y, Han Y, Gao C. Pressure-induced isostructural phase transition in CaB4. RSC Adv 2014. [DOI: 10.1039/c4ra04102j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|
12
|
Manghi F. Multi-orbital cluster perturbation theory for transition metal oxides. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:015602. [PMID: 24292335 DOI: 10.1088/0953-8984/26/1/015602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We present an extension of cluster perturbation theory to include many-body correlations associated with local e-e repulsion in real materials. We show that this approach can describe the physics of complex correlated materials where different atomic species and different orbitals coexist. The prototypical case of MnO is considered.
Collapse
Affiliation(s)
- F Manghi
- Dipartimento di Fisica, Università di Modena e Reggio Emilia and CNR, Institute of NanoSciences-S3, Via Campi 213/A, I-41125 Modena, Italy
| |
Collapse
|
13
|
Purwanto W, Zhang S, Krakauer H. Frozen-Orbital and Downfolding Calculations with Auxiliary-Field Quantum Monte Carlo. J Chem Theory Comput 2013; 9:4825-33. [DOI: 10.1021/ct4006486] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Wirawan Purwanto
- Department
of Physics, College of William and Mary, Williamsburg, Virginia 23187-8795, United States
| | - Shiwei Zhang
- Department
of Physics, College of William and Mary, Williamsburg, Virginia 23187-8795, United States
| | - Henry Krakauer
- Department
of Physics, College of William and Mary, Williamsburg, Virginia 23187-8795, United States
| |
Collapse
|
14
|
Saha D, Ranjan R, Swain D, Narayana C, Row TNG. An unusual temperature induced isostructural phase transition in a scheelite, Li(0.5)Ce(0.5)MoO4. Dalton Trans 2013; 42:7672-8. [PMID: 23538608 DOI: 10.1039/c3dt33033h] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High resolution synchrotron X-ray diffraction, dielectric and Raman scattering study of a scheelite compound Li0.5Ce0.5MoO4 (LCM) revealed that it transforms to a self similar structure above 400 °C. The thermally induced isostructural phase transition (IPT), a phenomenon which has rarely been reported in the literature, is preceded by partial softening of the zone centre phonons followed by their hardening above the IPT transition temperature. The high temperature isostructural phase, which exhibits expanded lattice parameters and cell volume, nucleates and grows in the low temperature matrix over a very wide temperature range. Both the phases show nearly identical thermal expansion suggesting similarities in symmetry, unaltered coordination environments around the atoms across the transition.
Collapse
Affiliation(s)
- Dipankar Saha
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012, India
| | | | | | | | | |
Collapse
|
15
|
Sharma S, Dewhurst JK, Shallcross S, Gross EKU. Spectral density and metal-insulator phase transition in Mott insulators within reduced density matrix functional theory. PHYSICAL REVIEW LETTERS 2013; 110:116403. [PMID: 25166559 DOI: 10.1103/physrevlett.110.116403] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Revised: 02/08/2013] [Indexed: 05/11/2023]
Abstract
We present a method for calculating the spectrum of periodic solids within reduced density matrix functional theory. This method is validated by a detailed comparison of the angular momentum projected spectral density with that of well-established many-body techniques, finding very good agreement in all cases. The physics behind the pressure induced insulator-metal phase transition in MnO is investigated. The driving mechanism of this transition is identified as increased crystal field splitting with pressure, resulting in a charge redistribution between the Mn e(g) and t(2)g symmetry projected states.
Collapse
Affiliation(s)
- S Sharma
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany
| | - J K Dewhurst
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany
| | - S Shallcross
- Lehrstuhl für Theoretische Festkörperphysik, Staudstrasse 7-B2, 91058 Erlangen, Germany
| | - E K U Gross
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany
| |
Collapse
|
16
|
Zhao Z, Zhou XF, Wang LM, Xu B, He J, Liu Z, Wang HT, Tian Y. Universal Phase Transitions of B1-Structured Stoichiometric Transition Metal Carbides. Inorg Chem 2011; 50:9266-72. [DOI: 10.1021/ic200356x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zhisheng Zhao
- State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China
| | - Xiang-Feng Zhou
- School of Physics and Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, Nankai University, Tianjin 300071, China
| | - Li-Min Wang
- State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China
| | - Bo Xu
- State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China
| | - Julong He
- State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China
| | - Zhongyuan Liu
- State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China
| | - Hui-Tian Wang
- School of Physics and Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, Nankai University, Tianjin 300071, China
| | - Yongjun Tian
- State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China
| |
Collapse
|
17
|
Musfeldt JL, Liu Z, Li S, Kang J, Lee C, Jena P, Manson JL, Schlueter JA, Carr GL, Whangbo MH. Pressure-Induced Local Structure Distortions in Cu(pyz)F2(H2O)2. Inorg Chem 2011; 50:6347-52. [PMID: 21644536 DOI: 10.1021/ic2008039] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- J. L. Musfeldt
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Z. Liu
- Geophysical Laboratory, Carnegie Institution of Washington, Washington, D.C. 20015, United States
| | - S. Li
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - J. Kang
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - C. Lee
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - P. Jena
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - J. L. Manson
- Department of Chemistry, and Biochemistry, Eastern Washington University, Cheney, Washington 99004, United States
| | - J. A. Schlueter
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - G. L. Carr
- National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - M.-H. Whangbo
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| |
Collapse
|
18
|
Large volume collapse observed in the phase transition in cubic PbCrO3 perovskite. Proc Natl Acad Sci U S A 2010; 107:14026-9. [PMID: 20660782 DOI: 10.1073/pnas.1005307107] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
When cubic PbCrO(3) perovskite (Phase I) is squeezed up to approximately 1.6 GPa at room temperature, a previously undetected phase (Phase II) has been observed with a 9.8% volume collapse. Because the structure of Phase II can also be indexed into a cubic perovskite as Phase I, the transition between Phases I and II is a cubic to cubic isostructural transition. Such a transition appears independent of the raw materials and synthesizing methods used for the cubic PbCrO(3) perovskite sample. In contrast to the high-pressure isostructural electronic transition that appears in Ce and SmS, this transition seems not related with any change of electronic state, but it could be possibly related on the abnormally large volume and compressibility of the PbCrO(3) Phase I. The physical mechanism behind this transition and the structural and electronic/magnetic properties of the condensed phases are the interesting issues for future studies.
Collapse
|
19
|
Ming X, Meng X, Hu F, Wang CZ, Huang ZF, Fan HG, Chen G. Pressure-induced magnetic moment collapse and insulator-to-semimetal transition in BiCoO(3). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:295902. [PMID: 21828538 DOI: 10.1088/0953-8984/21/29/295902] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The structural stability, magnetic properties and electronic structure of tetragonal BiCoO(3) under pressure have been studied by first-principles density functional calculations. The calculated results reveal that no tetragonal-to-cubic and ferroelectric-to-paraelectric phase transitions occur up to 30 GPa with a volume compression of about 25%. An electronic spin crossover transition of the Co(3+) ion from the high-spin to nonmagnetic low-spin configuration (magnetic moment collapse) occurs at 4 GPa by about 4.87% volume compression, which is concomitant with a first-order isosymmetric transition and an insulator-to-semimetal transition. The metallization in BiCoO(3) is driven by the spin-state transition at high pressure. Coexistence of the structural, spin-state and insulator-to-semimetal transitions implies that there is a strong coupling among the lattice, spin and charge degrees of freedom in BiCoO(3).
Collapse
Affiliation(s)
- Xing Ming
- Department of Materials Science, College of Materials Science and Engineering, Jilin University, Changchun 130012, People's Republic of China
| | | | | | | | | | | | | |
Collapse
|
20
|
Kunes J, Korotin DM, Korotin MA, Anisimov VI, Werner P. Pressure-driven metal-insulator transition in hematite from dynamical mean-field theory. PHYSICAL REVIEW LETTERS 2009; 102:146402. [PMID: 19392460 DOI: 10.1103/physrevlett.102.146402] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Indexed: 05/27/2023]
Abstract
The local density approximation combined with dynamical mean-field theory is applied to study the paramagnetic and magnetically ordered phases of hematite Fe2O3 as a function of volume. As the volume is decreased, a simultaneous first-order insulator-metal and high-spin to low-spin transition occurs close to the experimental value of the critical volume. The high-spin insulating phase is destroyed by a progressive reduction of the spectral gap with increasing pressure, upon closing of which the high-spin phase becomes unstable. We conclude that the transition in Fe2O3 at approximately 50 GPa can be described as an electronically driven volume collapse.
Collapse
Affiliation(s)
- J Kunes
- Theoretical Physics III, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, Augsburg 86135, Germany
| | | | | | | | | |
Collapse
|
21
|
Kostadinov IZ, Patton BR. Second critical point in first order metal-insulator transitions. PHYSICAL REVIEW LETTERS 2008; 101:226407. [PMID: 19113498 DOI: 10.1103/physrevlett.101.226407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2008] [Indexed: 05/27/2023]
Abstract
For first order metal-insulator transitions we show that, together with the dc conductance zero, there is a second critical point where the dielectric constant becomes zero and further turns negative. At this point the metallic reflectivity sharply increases. The two points can be separated by a phase separation state in a 3D disordered system but may tend to merge in 2D. For illustration we evaluate the dielectric function in a simple effective medium approximation and show that at the second point it turns negative. We reproduce the experimental data on a typical Mott insulator such as MnO, demonstrating the presence of the two points clearly. We discuss other experiments for studies of the phase separation state and a similar phase separation in superconductors with insulating inclusions.
Collapse
Affiliation(s)
- Ivan Z Kostadinov
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA.
| | | |
Collapse
|
22
|
Esler KP, Kim J, Ceperley DM, Purwanto W, Walter EJ, Krakauer H, Zhang S, Kent PRC, Hennig RG, Umrigar C, Bajdich M, Kolorenč J, Mitas L, Srinivasan A. Quantum Monte Carlo algorithms for electronic structure at the petascale; the Endstation project. ACTA ACUST UNITED AC 2008. [DOI: 10.1088/1742-6596/125/1/012057] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
23
|
Kunes J, Lukoyanov AV, Anisimov VI, Scalettar RT, Pickett WE. Collapse of magnetic moment drives the Mott transition in MnO. NATURE MATERIALS 2008; 7:198-202. [PMID: 18246073 DOI: 10.1038/nmat2115] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2007] [Accepted: 01/07/2008] [Indexed: 05/25/2023]
Abstract
The metal-insulator transition in correlated electron systems, where electron states transform from itinerant to localized, has been one of the central themes of condensed-matter physics for more than half a century. The persistence of this question has been a consequence both of the intricacy of the fundamental issues and the growing recognition of the complexities that arise in real materials, when strong repulsive interactions play the primary role. The initial concept of Mott was based on the relative importance of kinetic hopping (measured by the bandwidth) and onsite repulsion of electrons. Real materials, however, have many further degrees of freedom that, as is recently attracting note, give rise to a rich variety of scenarios for a 'Mott transition'. Here, we report results for the classic correlated insulator MnO that reproduce a simultaneous moment collapse, volume collapse and metallization transition near the observed pressure, and identify the mechanism as collapse of the magnetic moment due to an increase of crystal-field splitting, rather than to variation in the bandwidth.
Collapse
Affiliation(s)
- Jan Kunes
- Theoretical Physics III, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, Augsburg 86135, Germany.
| | | | | | | | | |
Collapse
|
24
|
Mattila A, Rueff JP, Badro J, Vankó G, Shukla A. Metal-ligand interplay in strongly correlated oxides: a parametrized phase diagram for pressure-induced spin transitions. PHYSICAL REVIEW LETTERS 2007; 98:196404. [PMID: 17677640 DOI: 10.1103/physrevlett.98.196404] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2006] [Indexed: 05/16/2023]
Abstract
We investigate the magnetic properties of archetypal transition-metal oxides MnO, FeO, CoO, and NiO under very high pressure by x-ray emission spectroscopy at the Kbeta line. We observe a strong modification of the magnetism in the megabar range in all the samples except NiO. The results are analyzed within a multiplet approach including charge-transfer effects. The spectral changes are well accounted for by changes of the ligand field acting on the d electrons and allows us to extract the d-hybridization strength, O-2p bandwidth and ionic crystal field across the magnetic transition. This approach allows first-hand insight into the mechanism of the pressure-induced spin transition.
Collapse
Affiliation(s)
- Aleksi Mattila
- Division of X-Ray Physics, Department of Physical Sciences, POB 64, 00014 University of Helsinki, Finland
| | | | | | | | | |
Collapse
|
25
|
Maddox BR, Lazicki A, Yoo CS, Iota V, Chen M, McMahan AK, Hu MY, Chow P, Scalettar RT, Pickett WE. 4f delocalization in Gd: inelastic x-ray scattering at ultrahigh pressure. PHYSICAL REVIEW LETTERS 2006; 96:215701. [PMID: 16803251 DOI: 10.1103/physrevlett.96.215701] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2005] [Indexed: 05/10/2023]
Abstract
We present resonant inelastic x-ray scattering and x-ray emission spectroscopy results on Gd metal to 113 GPa which suggest Kondo-like aspects in the delocalization of 4f electrons. Analysis of the resonant inelastic x-ray scattering data reveals a prolonged and continuous delocalization with volume throughout the entire pressure range, so that the volume-collapse transition at 59 GPa is only part of the phenomenon. Moreover, the Lgamma1 x-ray emission spectroscopy spectra indicate no apparent change in the bare 4f moment across the collapse, suggesting that Kondo screening is responsible for the expected Pauli-like behavior in magnetic susceptibility.
Collapse
Affiliation(s)
- B R Maddox
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Vankó G, Neisius T, Molnar G, Renz F, Karpati S, Shukla A, de Groot FMF. Probing the 3d Spin Momentum with X-ray Emission Spectroscopy: The Case of Molecular-Spin Transitions. J Phys Chem B 2006; 110:11647-53. [PMID: 16800459 DOI: 10.1021/jp0615961] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report X-ray emission spectra of Fe(III), Fe(II), and Co(II) spin-crossover compounds in their high-spin and low-spin forms. It is shown that all X-ray emission features are sensitive to the spin state. Variations of the Kbeta and the Kalpha emission line shapes, which are in agreement with theory, can be used as quantitative probes of the spin state; it is suggested that with appropriate reference experiments one can extract the spin momentum for a general case. Resonant X-ray emission spectra unveil details of the redistribution of electrons on the 3d levels associated with the spin-state change by revealing features at the X-ray absorption preedge not accessible through standard absorption measurements.
Collapse
Affiliation(s)
- György Vankó
- European Synchrotron Radiation Facility, BP 220 F-38043 Grenoble Cedex, France.
| | | | | | | | | | | | | |
Collapse
|