1
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Meekel EG, Nicholas TC, Slater B, Goodwin AL. Torsional flexibility in zinc-benzenedicarboxylate metal-organic frameworks. CrystEngComm 2024; 26:673-680. [PMID: 38293003 PMCID: PMC10823780 DOI: 10.1039/d3ce01078c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 12/26/2023] [Indexed: 02/01/2024]
Abstract
We explore the role and nature of torsional flexibility of carboxylate-benzene links in the structural chemistry of metal-organic frameworks (MOFs) based on Zn and benzenedicarboxlyate (bdc) linkers. A particular motivation is to understand the extent to which such flexibility is important in stabilising the unusual topologically aperiodic phase known as TRUMOF-1. We compare the torsion angle distributions of TRUMOF-1 models with those for crystalline Zn/1,3-bdc MOFs, including a number of new materials whose structures we report here. We find that both periodic and aperiodic Zn/1,3-bdc MOFs sample a similar range of torsion angles, and hence the formation of TRUMOF-1 does not require any additional flexibility beyond that already evident in chemically-related crystalline phases. Comparison with Zn/1,4-bdc MOFs does show, however, that the lower symmetry of the 1,3-bdc linker allows access to a broader range of torsion angles, reflecting a greater flexibility of this linker.
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Affiliation(s)
- Emily G Meekel
- Inorganic Chemistry Laboratory South Parks Road Oxford OX1 3QR UK
| | | | - Ben Slater
- Department of Chemistry, University College London 20 Gordon Street London WC1H 0AJ UK
| | - Andrew L Goodwin
- Inorganic Chemistry Laboratory South Parks Road Oxford OX1 3QR UK
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2
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Meekel EG, Schmidt EM, Cameron LJ, Dharma AD, Windsor HJ, Duyker SG, Minelli A, Pope T, Lepore GO, Slater B, Kepert CJ, Goodwin AL. Truchet-tile structure of a topologically aperiodic metal-organic framework. Science 2023; 379:357-361. [PMID: 36701437 DOI: 10.1126/science.ade5239] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
When tiles decorated to lower their symmetry are joined together, they can form aperiodic and labyrinthine patterns. Such Truchet tilings offer an efficient mechanism of visual data storage related to that used in barcodes and QR codes. We show that the crystalline metal-organic framework [OZn4][1,3-benzenedicarboxylate]3 (TRUMOF-1) is an atomic-scale realization of a complex three-dimensional Truchet tiling. Its crystal structure consists of a periodically arranged assembly of identical zinc-containing clusters connected uniformly in a well-defined but disordered fashion to give a topologically aperiodic microporous network. We suggest that this unusual structure emerges as a consequence of geometric frustration in the chemical building units from which it is assembled.
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Affiliation(s)
- Emily G Meekel
- Inorganic Chemistry Laboratory, University of Oxford, Oxford OX1 3QR, UK
| | - Ella M Schmidt
- Inorganic Chemistry Laboratory, University of Oxford, Oxford OX1 3QR, UK.,Fachbereich Geowissenschaften, Universität Bremen, D-28359 Bremen, Germany
| | - Lisa J Cameron
- School of Chemistry, University of Sydney, New South Wales 2006, Australia
| | - A David Dharma
- School of Chemistry, University of Sydney, New South Wales 2006, Australia
| | - Hunter J Windsor
- School of Chemistry, University of Sydney, New South Wales 2006, Australia
| | - Samuel G Duyker
- School of Chemistry, University of Sydney, New South Wales 2006, Australia.,Sydney Analytical, Core Research Facilities, University of Sydney, New South Wales 2006, Australia
| | - Arianna Minelli
- Inorganic Chemistry Laboratory, University of Oxford, Oxford OX1 3QR, UK
| | - Tom Pope
- Department of Chemistry, University College London, London WC1H 0AJ, UK
| | | | - Ben Slater
- Department of Chemistry, University College London, London WC1H 0AJ, UK
| | - Cameron J Kepert
- School of Chemistry, University of Sydney, New South Wales 2006, Australia
| | - Andrew L Goodwin
- Inorganic Chemistry Laboratory, University of Oxford, Oxford OX1 3QR, UK
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3
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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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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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4
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Syzranov SV, Ramirez AP. Eminuscent phase in frustrated magnets: a challenge to quantum spin liquids. Nat Commun 2022; 13:2993. [PMID: 35637214 PMCID: PMC9151641 DOI: 10.1038/s41467-022-30739-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 05/16/2022] [Indexed: 12/04/2022] Open
Abstract
A geometrically frustrated (GF) magnet consists of localised magnetic moments, spins, whose orientation cannot be arranged to simultaneously minimise their interaction energies. Such materials may host novel fascinating phases of matter, such as fluid-like states called quantum spin-liquids. GF magnets have, like all solid-state systems, randomly located impurities whose magnetic moments may “freeze” at low temperatures, making the system enter a spin-glass state. We analyse the available data for spin-glass transitions in GF materials and find a surprising trend: the glass-transition temperature grows with decreasing impurity concentration and reaches a finite value in the impurity-free limit at a previously unidentified, “hidden”, energy scale. We propose a scenario in which the interplay of interactions and entropy leads to a crossover in the permeability of the medium that assists glass freezing at low temperatures. This low-temperature, “eminuscent”, phase may obscure or even destroy the widely-sought spin-liquid states in rather clean systems. A spin-glass forms in frustrated magnetic systems when at low temperatures impurity sites “freeze” into a random spin configuration. Here, by looking back at previous experimental results, Syzranov and Ramirez show that the glass-transition temperature grows with decreasing impurity concentration.
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5
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Chepkemboi C, Jorgensen K, Sato J, Laurita G. Strategies and Considerations for Least-Squares Analysis of Total Scattering Data. ACS OMEGA 2022; 7:14402-14411. [PMID: 35572759 PMCID: PMC9089679 DOI: 10.1021/acsomega.2c01285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 04/06/2022] [Indexed: 06/15/2023]
Abstract
The process of least-squares analysis has been applied for decades in the field of crystallography. Here, we discuss the application of this process to total scattering data, primarily in the combination of least-squares Rietveld refinements and fitting of the atomic pair distribution function (PDF). While these two approaches use the same framework, the interpretation of results from least-squares fitting of PDF data should be done with caution through carefully constructed analysis approaches. We provide strategies and considerations for applying least-squares analysis to total scattering data, combining both crystallographic Rietveld and fitting of PDF data, given in context with recent examples from the literature. This perspective is aimed to be an accessible document for those new to the total scattering approach, as well as a reflective framework for the total scattering expert.
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6
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Coates CS, Baise M, Schmutzler A, Simonov A, Makepeace JW, Seel AG, Smith RI, Playford HY, Keen DA, Siegel R, Senker J, Slater B, Goodwin AL. Spin-ice physics in cadmium cyanide. Nat Commun 2021; 12:2272. [PMID: 33859176 PMCID: PMC8050284 DOI: 10.1038/s41467-021-22515-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 03/16/2021] [Indexed: 11/08/2022] Open
Abstract
Spin-ices are frustrated magnets that support a particularly rich variety of emergent physics. Typically, it is the interplay of magnetic dipole interactions, spin anisotropy, and geometric frustration on the pyrochlore lattice that drives spin-ice formation. The relevant physics occurs at temperatures commensurate with the magnetic interaction strength, which for most systems is 1-5 K. Here, we show that non-magnetic cadmium cyanide, Cd(CN)2, exhibits analogous behaviour to magnetic spin-ices, but does so on a temperature scale that is nearly two orders of magnitude greater. The electric dipole moments of cyanide ions in Cd(CN)2 assume the role of magnetic pseudospins, with the difference in energy scale reflecting the increased strength of electric vs magnetic dipolar interactions. As a result, spin-ice physics influences the structural behaviour of Cd(CN)2 even at room temperature.
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Affiliation(s)
- Chloe S Coates
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, Oxford, UK
| | - Mia Baise
- Department of Chemistry, University College London, London, UK
| | | | - Arkadiy Simonov
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, Oxford, UK
- Department of Materials, ETH Zurich, Zurich, Switzerland
| | - Joshua W Makepeace
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, Oxford, UK
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham, UK
| | - Andrew G Seel
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, Oxford, UK
- Department of Physics and Astronomy, University College London, London, UK
| | - Ronald I Smith
- ISIS Facility, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire, UK
| | - Helen Y Playford
- ISIS Facility, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire, UK
| | - David A Keen
- ISIS Facility, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire, UK
| | - Renée Siegel
- Anorganische Chemie III, University of Bayreuth, Bayreuth, Germany
| | - Jürgen Senker
- Anorganische Chemie III, University of Bayreuth, Bayreuth, Germany
| | - Ben Slater
- Department of Chemistry, University College London, London, UK.
| | - Andrew L Goodwin
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, Oxford, UK.
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7
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Simonov A, Goodwin AL. Designing disorder into crystalline materials. Nat Rev Chem 2020; 4:657-673. [PMID: 37127977 DOI: 10.1038/s41570-020-00228-3] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/15/2020] [Indexed: 01/21/2023]
Abstract
Crystals are a state of matter characterized by periodic order. Yet, crystalline materials can harbour disorder in many guises, such as non-repeating variations in composition, atom displacements, bonding arrangements, molecular orientations, conformations, charge states, orbital occupancies or magnetic structure. Disorder can sometimes be random but, more usually, it is correlated. Frontier research into disordered crystals now seeks to control and exploit the unusual patterns that persist within these correlated disordered states in order to access functional responses inaccessible to conventional crystals. In this Review, we survey the core design principles that guide targeted control over correlated disorder. We show how these principles - often informed by long-studied statistical mechanical models - can be applied across an unexpectedly broad range of materials, including organics, supramolecular assemblies, oxide ceramics and metal-organic frameworks. We conclude with a forward-looking discussion of the exciting link between disorder and function in responsive media, thermoelectrics and topological phases.
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8
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Semeno AV, Anisimov MA, Bogach AV, Demishev SV, Gilmanov MI, Filipov VB, Shitsevalova NY, Glushkov VV. Role of spin-glass behavior in the formation of exotic magnetic states in GdB 6. Sci Rep 2020; 10:18214. [PMID: 33106511 PMCID: PMC7589464 DOI: 10.1038/s41598-020-75327-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 10/06/2020] [Indexed: 11/18/2022] Open
Abstract
Randomness and frustration are believed to be two crucial criteria for the formation of spin glass state. However, the spin freezing occurs in some well-ordered crystals below the related temperature Tf due to the instability of each spin state, which induces the variation of either magnetic moment value or exchange energy. Here we explore the new mechanism of the in-site originated disorder in antiferromagnets Gd0.73La0.27B6 and GdB6, which is caused by the random mutual shifts of Gd3+ spins from the centrally symmetrical positions in the regular cubic lattice. The universal scaling of ESR linewidth temperature dependencies to the power law ΔH(T) ~ ((T − TD)/TD)α with α = − 1.1 ± 0.05 in the paramagnetic phase of both compounds demonstrates the identity of the origin of magnetic randomness. In Gd0.73La0.27B6 the resulting random spin configurations freeze at Tf ≈ 10.5 K where the maximum of magnetization is observed. Below Tf the splitting of ZFC and FC magnetization curves takes place as well as the magnetic state depends on the antecedent sample history. In the case of GdB6 the coherent displacement of Gd ions compete with these random shifts forming an antiferromagnetic (AFM) phase at TN = 15.5 K, which prevails over the spin freezing at Tf ≈ 13 K, expected from the ESR data. The observation of the hysteresis of the ESR spectrum in the AFM phase suggests that its properties may be determined by the competition of two types of AFM orders, which results in formation of stable magnetic domains with nonequivalent positions of AFM Gd pairs at T < 10 K.
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Affiliation(s)
- A V Semeno
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilov str. 38, Moscow, 119991, Russia.
| | - M A Anisimov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilov str. 38, Moscow, 119991, Russia
| | - A V Bogach
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilov str. 38, Moscow, 119991, Russia
| | - S V Demishev
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilov str. 38, Moscow, 119991, Russia.,National Research University Higher School of Economics, Myasnitskaya str. 20, Moscow, 101000, Russia
| | - M I Gilmanov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilov str. 38, Moscow, 119991, Russia
| | - V B Filipov
- Frantsevich Institute for Problems of Materials Science NAS, Krzhyzhanovsky str. 3, Kiev, 03680, Ukraine
| | - N Yu Shitsevalova
- Frantsevich Institute for Problems of Materials Science NAS, Krzhyzhanovsky str. 3, Kiev, 03680, Ukraine
| | - V V Glushkov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilov str. 38, Moscow, 119991, Russia
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9
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Mitsumoto K, Hotta C, Yoshino H. Spin-Orbital Glass Transition in a Model of a Frustrated Pyrochlore Magnet without Quenched Disorder. PHYSICAL REVIEW LETTERS 2020; 124:087201. [PMID: 32167313 DOI: 10.1103/physrevlett.124.087201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 12/09/2019] [Accepted: 01/21/2020] [Indexed: 06/10/2023]
Abstract
We show theoretically that spin and orbital degrees of freedom in the pyrochlore oxide Y_{2}Mo_{2}O_{7}, which is free of quenched disorder, can exhibit a simultaneous glass transition, working as dynamical disorder for each other. The interplay of spins and orbitals is mediated by the Jahn-Teller lattice distortion that selects the choice of orbitals, which then generates variant spin exchange interactions ranging from ferromagnetic to antiferromagnetic ones. Our Monte Carlo simulations detect the power-law divergence of the relaxation times and the negative divergence of both the magnetic and dielectric nonlinear susceptibilities, resolving the long-standing puzzle on the origin of the disorder-free spin glass.
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Affiliation(s)
- Kota Mitsumoto
- Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Chisa Hotta
- Department of Basic Science, University of Tokyo, Tokyo 153-8902, Japan
| | - Hajime Yoshino
- Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
- Cybermedia Center, Osaka University, Toyonaka, Osaka 560-0043, Japan
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10
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Shinaoka H, Motome Y, Miyake T, Ishibashi S, Werner P. First-principles studies of spin-orbital physics in pyrochlore oxides. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:323001. [PMID: 31140447 DOI: 10.1088/1361-648x/ab162f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The pyrochlore oxides [Formula: see text]O7 exhibit a complex interplay between geometrical frustration, electronic correlations, and spin-orbit coupling (SOC), due to the lattice structure and active charge, spin, and orbital degrees of freedom. Understanding the properties of these materials is a theoretical challenge, because their intricate nature depends on material-specific details and quantum many-body effects. Here we review our recent studies based on first-principles calculations and quantum many-body theories for 4d and 5d pyrochlore oxides with B = Mo, Os, and Ir. In these studies, the SOC and local electron correlations are treated within the local density approximation (LDA) + U and LDA + dynamical mean-field theory formalisms. We also discuss the technical aspects of these calculations.
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Affiliation(s)
- Hiroshi Shinaoka
- Department of Physics, Saitama University, Saitama 338-8570, Japan
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11
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Bozin ES, Yin WG, Koch RJ, Abeykoon M, Hor YS, Zheng H, Lei HC, Petrovic C, Mitchell JF, Billinge SJL. Local orbital degeneracy lifting as a precursor to an orbital-selective Peierls transition. Nat Commun 2019; 10:3638. [PMID: 31409783 PMCID: PMC6692321 DOI: 10.1038/s41467-019-11372-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 07/09/2019] [Indexed: 11/25/2022] Open
Abstract
Fundamental electronic principles underlying all transition metal compounds are the symmetry and filling of the d-electron orbitals and the influence of this filling on structural configurations and responses. Here we use a sensitive local structural technique, x-ray atomic pair distribution function analysis, to reveal the presence of fluctuating local-structural distortions at high temperature in one such compound, CuIr2S4. We show that this hitherto overlooked fluctuating symmetry-lowering is electronic in origin and will modify the energy-level spectrum and electronic and magnetic properties. The explanation is a local, fluctuating, orbital-degeneracy-lifted state. The natural extension of our result would be that this phenomenon is likely to be widespread amongst diverse classes of partially filled nominally degenerate d-electron systems, with potentially broad implications for our understanding of their properties. A common feature of many transition metal materials is global symmetry breaking at low temperatures. Here the authors show that such materials are characterized by fluctuating symmetry-lowering distortions that exist pre-formed in higher temperature phases with greater average symmetry.
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Affiliation(s)
- E S Bozin
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA.
| | - W G Yin
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - R J Koch
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - M Abeykoon
- Photon Sciences Division, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Y S Hor
- Materials Science Division, Argonne National Laboratory, Argonne, IL, 60439, USA.,Department of Physics, Missouri University of Science and Technology, Rolla, MO, 65409, USA
| | - H Zheng
- Materials Science Division, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - H C Lei
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA.,Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials and Micro-nano Devices, Renmin University of China, 100872, Beijing, China
| | - C Petrovic
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - J F Mitchell
- Materials Science Division, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - S J L Billinge
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA. .,Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, 10027, USA.
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12
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Smerald A, Jackeli G. Giant Magnetoelastic-Coupling Driven Spin-Lattice Liquid State in Molybdate Pyrochlores. PHYSICAL REVIEW LETTERS 2019; 122:227202. [PMID: 31283258 DOI: 10.1103/physrevlett.122.227202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 03/29/2019] [Indexed: 06/09/2023]
Abstract
We propose the idea of a spin-lattice liquid, in which spin and lattice degrees of freedom are strongly coupled and remain disordered and fluctuating down to low temperatures. We show that such a state arises naturally from a microscopic analysis of a class of molybdate pyrochlore compounds, and is driven by a giant magnetoelastic effect. Finally, we argue that this could explain some of the experimental features of Y_{2}Mo_{2}O_{7}.
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Affiliation(s)
- Andrew Smerald
- Max Planck Institut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany
| | - George Jackeli
- Max Planck Institut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany
- Insitute for Functional Matter and Quantum Technologies, University of Stuttgart, Pfaffenwaldring 57, D-70569 Stuttgart, Germany
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13
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Paddison JAM. Ultrafast calculation of diffuse scattering from atomistic models. ACTA CRYSTALLOGRAPHICA A-FOUNDATION AND ADVANCES 2019; 75:14-24. [PMID: 30575580 DOI: 10.1107/s2053273318015632] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 11/05/2018] [Indexed: 11/11/2022]
Abstract
Diffuse scattering is a rich source of information about disorder in crystalline materials, which can be modelled using atomistic techniques such as Monte Carlo and molecular dynamics simulations. Modern X-ray and neutron scattering instruments can rapidly measure large volumes of diffuse-scattering data. Unfortunately, current algorithms for atomistic diffuse-scattering calculations are too slow to model large data sets completely, because the fast Fourier transform (FFT) algorithm has long been considered unsuitable for such calculations [Butler & Welberry (1992). J. Appl. Cryst. 25, 391-399]. Here, a new approach is presented for ultrafast calculation of atomistic diffuse-scattering patterns. It is shown that the FFT can actually be used to perform such calculations rapidly, and that a fast method based on sampling theory can be used to reduce high-frequency noise in the calculations. These algorithms are benchmarked using realistic examples of compositional, magnetic and displacive disorder. They accelerate the calculations by a factor of at least 102, making refinement of atomistic models to large diffuse-scattering volumes practical.
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Affiliation(s)
- Joseph A M Paddison
- Churchill College, University of Cambridge, Storey's Way, Cambridge CB3 0DS, United Kingdom
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14
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Cai Y, Wilson MN, Hallas AM, Liu L, Frandsen BA, Dunsiger SR, Krizan JW, Cava RJ, Rubel O, Uemura YJ, Luke GM. μSR study of spin freezing and persistent spin dynamics in NaCaNi 2F 7. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:385802. [PMID: 30089706 DOI: 10.1088/1361-648x/aad91c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A new pyrochlore compound, NaCaNi2F7, was recently synthesized and has a single magnetic site with spin-1 Ni2+ . We present zero field and longitudinal field muon spin rotation (μSR) measurements on this pyrochlore. Density functional theory calculations show that the most likely muon site is located between two fluorine ions, but off-centre. A characteristic F-μ-F muon spin polarization function is observed at high temperatures where Ni spin fluctuations are sufficiently rapid. The Ni2+ spins undergo spin freezing into a disordered ground state below 4 K, with a characteristic internal field strength of 140 G. Persistent Ni spin dynamics are present to our lowest temperatures (75 mK), a feature characteristic of many geometrically frustrated magnetic systems.
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Affiliation(s)
- Y Cai
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada
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15
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Trump BA, Koohpayeh SM, Livi KJT, Wen JJ, Arpino KE, Ramasse QM, Brydson R, Feygenson M, Takeda H, Takigawa M, Kimura K, Nakatsuji S, Broholm CL, McQueen TM. Universal geometric frustration in pyrochlores. Nat Commun 2018; 9:2619. [PMID: 29976983 PMCID: PMC6033937 DOI: 10.1038/s41467-018-05033-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 06/05/2018] [Indexed: 11/28/2022] Open
Abstract
Materials with the pyrochlore/fluorite structure have diverse technological applications, from magnetism to nuclear waste disposal. Here we report the observation of structural instability present in the pyrochlores A2Zr2O6Oʹ (A = Pr, La) and Yb2Ti2O6Oʹ, that exists despite ideal stoichiometry, ideal cation-ordering, the absence of lone pair effects, and a lack of magnetic order. Though these materials appear to have good long-range order, local structure probes find displacements, of the order of 0.01 nm, within the pyrochlore framework. The pattern of displacements of the A2Oʹ sublattice mimics the entropically-driven fluxional motions characteristic of and well-known in the silica mineral β-cristobalite. The universality of such displacements within the pyrochlore structure adds to the known structural diversity and explains the extreme sensitivity to composition found in quantum spin ices and the lack of ferroelectric behavior in pyrochlores. The family of pyrochlore complex oxides includes many materials of fundamental or practical interest, such as spin ices and dielectrics. Trump et al. show that flexibility of the pyrochlores’ structure leads to local displacements that explain some of their unusual physical properties.
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Affiliation(s)
- B A Trump
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA.,Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA.,Department of Physics and Astronomy, Institute for Quantum Matter, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - S M Koohpayeh
- Department of Physics and Astronomy, Institute for Quantum Matter, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - K J T Livi
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - J-J Wen
- Department of Physics and Astronomy, Institute for Quantum Matter, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - K E Arpino
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA.,Department of Physics and Astronomy, Institute for Quantum Matter, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Q M Ramasse
- SuperSTEM Laboratory, STFC Daresbury Campus, Daresbury, WA4 4AD, UK
| | - R Brydson
- School of Chemical and Process Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - M Feygenson
- Jülich Center for Neutron Science, Forschungszentrum Jülich GmbH, D-52425, Jülich, Germany
| | - H Takeda
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - M Takigawa
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - K Kimura
- Division of Materials Physics, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, 560-8531, Japan
| | - S Nakatsuji
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - C L Broholm
- Department of Physics and Astronomy, Institute for Quantum Matter, Johns Hopkins University, Baltimore, MD, 21218, USA.,Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - T M McQueen
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA. .,Department of Physics and Astronomy, Institute for Quantum Matter, Johns Hopkins University, Baltimore, MD, 21218, USA. .,Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA.
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16
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Baise M, Maffettone PM, Trousselet F, Funnell NP, Coudert FX, Goodwin AL. Negative Hydration Expansion in ZrW_{2}O_{8}: Microscopic Mechanism, Spaghetti Dynamics, and Negative Thermal Expansion. PHYSICAL REVIEW LETTERS 2018; 120:265501. [PMID: 30004783 DOI: 10.1103/physrevlett.120.265501] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Indexed: 06/08/2023]
Abstract
We use a combination of x-ray diffraction, total scattering, and quantum mechanical calculations to determine the mechanism responsible for hydration-driven contraction in ZrW_{2}O_{8}. The inclusion of H_{2}O molecules within the ZrW_{2}O_{8} network drives the concerted formation of new W─O bonds to give one-dimensional (─W─O─)_{n} strings. The topology of the ZrW_{2}O_{8} network is such that there is no unique choice for the string trajectories: the same local changes in coordination can propagate with a large number of different periodicities. Consequently, ZrW_{2}O_{8}·H_{2}O is heavily disordered, with each configuration of strings forming a dense aperiodic "spaghetti." This new connectivity contracts the unit cell via large shifts in the Zr and W atom positions. Fluctuations of the undistorted parent structure towards this spaghetti phase emerge as the key negative thermal expansion (NTE) phonon modes in ZrW_{2}O_{8} itself. The large relative density of NTE phonon modes in ZrW_{2}O_{8} actually reflects the degeneracy of volume-contracting spaghetti excitations, itself a function of the particular topology of this remarkable material.
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Affiliation(s)
- Mia Baise
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR, United Kingdom
- Department of Chemistry, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Phillip M Maffettone
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Fabien Trousselet
- Chimie ParisTech, PSL Research University, CNRS, Institut de Recherche de Chimie Paris, 75005 Paris, France
| | - Nicholas P Funnell
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR, United Kingdom
- ISIS Neutron and Muon Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
| | - François-Xavier Coudert
- Chimie ParisTech, PSL Research University, CNRS, Institut de Recherche de Chimie Paris, 75005 Paris, France
| | - Andrew L Goodwin
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR, United Kingdom
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17
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Romhányi J, Balents L, Jackeli G. Spin-Orbit Dimers and Noncollinear Phases in d^{1} Cubic Double Perovskites. PHYSICAL REVIEW LETTERS 2017; 118:217202. [PMID: 28598662 DOI: 10.1103/physrevlett.118.217202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Indexed: 06/07/2023]
Abstract
We formulate and study a spin-orbital model for a family of cubic double perovskites with d^{1} ions occupying a frustrated fcc sublattice. A variational approach and a complementary analytical analysis reveal a rich variety of phases emerging from the interplay of Hund's rule and spin-orbit coupling. The phase digram includes noncollinear ordered states, with or without a net moment, and, remarkably, a large window of a nonmagnetic disordered spin-orbit dimer phase. The present theory uncovers the physical origin of the unusual amorphous valence bond state experimentally suggested for Ba_{2}BMoO_{6} (B=Y, Lu) and predicts possible ordered patterns in Ba_{2}BOsO_{6} (B=Na, Li) compounds.
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Affiliation(s)
- Judit Romhányi
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
- Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa 904-0395, Japan
| | - Leon Balents
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106, USA
| | - George Jackeli
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
- Institute for Functional Matter and Quantum Technologies, University of Stuttgart, Pfaffenwaldring 57, D-70569 Stuttgart, Germany
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