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Simpson S, Milton M, Fop S, Stenning GBG, Hopper HA, Ritter C, Mclaughlin AC. Localized Spin Dimers and Structural Distortions in the Hexagonal Perovskite Ba 3CaMo 2O 9. Inorg Chem 2022; 61:11622-11628. [PMID: 35852971 PMCID: PMC9377418 DOI: 10.1021/acs.inorgchem.2c01102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Indexed: 11/29/2022]
Abstract
Extended solid-state materials based on the hexagonal perovskite framework are typified by close competition between localized magnetic interactions and quasi-molecular electronic states. Here, we report the structural and magnetic properties of the new six-layer hexagonal perovskite Ba3CaMo2O9. Neutron diffraction experiments, combined with magnetic susceptibility measurements, show that the Mo2O9 dimers retain localized character down to 5 K and adopt nonmagnetic spin-singlet ground states. This is in contrast to the recently reported Ba3SrMo2O9 analogue, in which the Mo2O9 dimers spontaneously separate into a mixture of localized and quasi-molecular ground states. Structural distortions in both Ba3CaMo2O9 and Ba3SrMo2O9 have been studied with the aid of distortion mode analyses to elucidate the coupling between the crystal lattice and electronic interactions in 6H Mo5+ hexagonal perovskites.
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Affiliation(s)
- Struan Simpson
- Chemistry
Department, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, U.K.
| | - Michael Milton
- Chemistry
Department, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, U.K.
| | - Sacha Fop
- Chemistry
Department, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, U.K.
| | - Gavin B. G. Stenning
- ISIS
Experimental Operations Division, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 0QX, U.K.
| | | | - Clemens Ritter
- Institut
Laue Langevin, 71 Avenue
des Martyrs, F-38042 Grenoble Cedex 9, France
| | - Abbie C. Mclaughlin
- Chemistry
Department, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, U.K.
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Aguilar-Maldonado C, Mentré O, Tsirlin AA, Ritter C, Missiul A, Fauth F, Arévalo-López AM. Hybrid electrons in the trimerized GaV 4O 8. MATERIALS HORIZONS 2021; 8:2325-2329. [PMID: 34846437 DOI: 10.1039/d1mh00390a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Mixed-valent transition-metal compounds display complex structural, electronic and magnetic properties, which often intricately coexist. Here, we report the new ternary oxide GaV4O8, a structural sibling of skyrmion-hosting lacunar spinels. GaV4O8 contains a vanadium trimer and an original spin-orbital-charge texture that forms upon the structural phase transition at TS = 68 K followed by the magnetic transition at TN = 35 K. The texture arises from the coexistence of orbital molecules on the vanadium trimers and localized electrons on the remaining vanadium atoms. Such hybrid electrons create opportunities for novel types of spin, charge, and orbital order in mixed-valent transition-metal compounds.
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Affiliation(s)
- Cintli Aguilar-Maldonado
- Université Lille Nord de France, UMR 8181 CNRS, Unité de Catalyse et de Chimie du Solide (UCCS USTL), Villeneuve d'Ascq F-59655, France.
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Site-selective doping of ordered charge states in magnetite. Nat Commun 2020; 11:1671. [PMID: 32245968 PMCID: PMC7125154 DOI: 10.1038/s41467-020-15504-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 03/13/2020] [Indexed: 11/24/2022] Open
Abstract
Charge ordering creates a spontaneous array of differently charged ions and is associated with electronic phenomena such as superconductivity, colossal magnetoresistances (CMR), and multiferroicity. Charge orders are usually suppressed by chemical doping and site selective doping of a charge ordered array has not previously been demonstrated. Here we show that selective oxidation of one out of eight distinct Fe2+ sites occurs within the complex Fe2+/Fe3+ ordered structure of 2%-doped magnetite (Fe3O4), while the rest of the charge and orbitally ordered network remains intact. This ‘charge order within a charge order’ is attributed to the relative instability of the trimeron distortion surrounding the selected site. Our discovery suggests that similar complex charge ordered arrays could be used to provide surface sites for selective redox reactions, or for storing information by doping specific sites. Charge ordering in magnetite is an important example of the complex behaviour that emerges in transition metal oxides. Here the authors show that doping causes selective oxidation of one site in the established trimeron pattern, introducing an additional charge-ordered structure.
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Liu J, Wang X, Borkiewicz OJ, Hu E, Xiao RJ, Chen L, Page K. Unified View of the Local Cation-Ordered State in Inverse Spinel Oxides. Inorg Chem 2019; 58:14389-14402. [PMID: 31625736 DOI: 10.1021/acs.inorgchem.9b01685] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Cation ordering/disordering in spinel oxides plays an essential role in the rich physical and chemical properties which are hallmarks of the structural archetype. A variety of cation-ordering motifs have been reported for spinel oxides with multiple cations residing on the octahedral site (or B-site). This has attracted tremendous attention from both experimental and theoretical communities in the last few decades. However, no unified view has been reached, presumably due to the richness of cation species and corresponding complex arrangements emergent in this large family of compounds. In this report, local cation-ordered ground states of (inverse) spinel oxides with two different cations on the octahedral site have been thoroughly investigated using neutron and X-ray total scattering, and a comprehensive theory has been proposed to explain the commonly observed cation-ordered polymorphs. It is found that a cation-zigzag-ordered structure (space group P4122) is the ground state for inverse spinel oxides with a pure or strong ionic lattice, while a cation-linear-ordered arrangement (space group Imma) emerges when one of the B-site cations forms very strong directional covalent bonds with lattice oxygen. The degree and length scale of cation ordering is strongly correlated with the charge and ionic radius difference between the two octahedral site cations. More complicated cation ordering schemes can be formed when there is a concomitant charge and orbital ordering which fall on a similar energy scale. This can lead to the formation of orbital-driven cation clusters or the broad concept of "molecules" in solid- state compounds. It is expected these findings will help to better understand the observed physical properties of spinel oxides and thus facilitate design strategies for improved functional materials.
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Affiliation(s)
- Jue Liu
- Neutron Scattering Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee , 37831 , United States
| | - Xuelong Wang
- Chemistry Division , Brookhaven National Laboratory , Upton , New York , 11973 , United States.,Institute of Physics Chinese Academy of Sciences , 100190 Beijing , China
| | - Olaf J Borkiewicz
- X-ray Science Division, Advanced Photon Source , Argonne National Laboratory , Argonne , Illinois 60439 , United States
| | - Enyuan Hu
- Chemistry Division , Brookhaven National Laboratory , Upton , New York , 11973 , United States
| | - Rui-Juan Xiao
- Institute of Physics Chinese Academy of Sciences , 100190 Beijing , China
| | - Liquan Chen
- Institute of Physics Chinese Academy of Sciences , 100190 Beijing , China
| | - Katharine Page
- Neutron Scattering Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee , 37831 , United States
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Co-emergence of magnetic order and structural fluctuations in magnetite. Nat Commun 2019; 10:2857. [PMID: 31253806 PMCID: PMC6599026 DOI: 10.1038/s41467-019-10949-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 06/10/2019] [Indexed: 11/09/2022] Open
Abstract
The nature of the Verwey transition occurring at TV ≈ 125 K in magnetite (Fe3O4) has been an outstanding problem over many decades. A complex low temperature electronic order was recently discovered and associated structural fluctuations persisting above TV are widely reported, but the origin of the underlying correlations and hence of the Verwey transition remains unclear. Here we show that local structural fluctuations in magnetite emerge below the Curie transition at TC ≈ 850 K, through X-ray pair distribution function analysis. Around 80% of the low temperature correlations emerge in proportion to magnetization below TC. This confirms that fluctuations in Fe-Fe bonding arising from magnetic order are the primary electronic instability and hence the origin of the Verwey transition. Such hidden instabilities may be important to other spin-polarised conductors and orbitally degenerate materials.
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Kobayashi S, Katayama N, Manjo T, Ueda H, Michioka C, Sugiyama J, Sassa Y, Forslund OK, Månsson M, Yoshimura K, Sawa H. Linear Trimer Formation with Antiferromagnetic Ordering in 1T-CrSe2 Originating from Peierls-like Instabilities and Interlayer Se–Se Interactions. Inorg Chem 2019; 58:14304-14315. [DOI: 10.1021/acs.inorgchem.9b00186] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Shintaro Kobayashi
- Department of Applied Physics, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
| | - Naoyuki Katayama
- Department of Applied Physics, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
| | - Taishun Manjo
- Department of Applied Physics, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
| | - Hiroaki Ueda
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Chishiro Michioka
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Jun Sugiyama
- Toyota Central Research & Development Laboratories, Inc., Nagakute, Aichi 480-1192, Japan
| | - Yasmine Sassa
- Department of Physics & Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden
- Department of Physics, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
| | - Ola Kenji Forslund
- Department of Applied Physics, KTH Royal Institute of Technology, Electrum 229, SE-16440 Stockholm Kista, Sweden
| | - Martin Månsson
- Department of Applied Physics, KTH Royal Institute of Technology, Electrum 229, SE-16440 Stockholm Kista, Sweden
| | - Kazuyoshi Yoshimura
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
- Research Center for Low Temperature and Material Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Hiroshi Sawa
- Department of Applied Physics, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
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Talanov MV, Shirokov VB, Avakyan LA, Talanov VM, Borlakov KS. Vanadium clusters formation in geometrically frustrated spinel oxide AlV 2O 4. ACTA CRYSTALLOGRAPHICA SECTION B, STRUCTURAL SCIENCE, CRYSTAL ENGINEERING AND MATERIALS 2018; 74:337-353. [PMID: 30141419 DOI: 10.1107/s2052520618007242] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Accepted: 05/14/2018] [Indexed: 06/08/2023]
Abstract
The spinel oxide AlV2O4 is a unique material, in which the formation of clusters is accompanied by atomic, charge and orbital ordering and a rhombohedral lattice distortion. In this work a theory of the structural phase transition in AlV2O4 is proposed. This theory is based on the study of the order-parameter symmetry, thermodynamics, electron density distribution, crystal chemistry and mechanisms of formation of the atomic and orbital structures of the rhombohedral phase. It is established that the critical order parameter is transformed according to irreducible representation k9(τ4) (in Kovalev notation) of the Fd \bar{3}m space group. Knowledge of the order-parameter symmetry allows us to show that the derived AlV2O4 rhombohedral structure is a result of displacements of all atom types and the ordering of Al atoms (1:1 order type in tetrahedral spinel sites), V atoms (1:1:6 order type in octahedral sites) and O atoms (1:1:3:3 order type), and the ordering of dxy, dxz and dyz orbitals. Application of the density functional theory showed that V atoms in the Kagomé sublattice formed separate trimers. Also, no sign of metallic bonding between separate vanadium trimers in the heptamer structure was found. The density functional theory study and the crystal chemical analysis of V-O bond lengths allowed us to assume the existence of dimers and trimers as main clusters in the structure of the AlV2O4 rhombohedral modification. The trimer model of the low-symmetry AlV2O4 structure is proposed. Within the Landau theory of phase transitions, typical diagrams of possible phase states are built. It is shown that phase states can be changed as a first-order phase transition close to the second order in the vicinity of tricritical points of the phase diagrams.
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Affiliation(s)
| | | | - Leon A Avakyan
- Southern Federal University, Rostov-on-Don, Russian Federation
| | - Valeriy M Talanov
- South-Russian State Polytechnic University, Novocherkassk, Russian Federation
| | - Khisa Sh Borlakov
- North Caucasian State Humanitarian and Technological Academy, Cherkessk, Russian Federation
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