1
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Abstract
Quantum spin liquids are an exciting playground for exotic physical phenomena and emergent many-body quantum states. The realization and discovery of quantum spin liquid candidate materials and associated phenomena lie at the intersection of solid-state chemistry, condensed matter physics, and materials science and engineering. In this review, we provide the current status of the crystal chemistry, synthetic techniques, physical properties, and research methods in the field of quantum spin liquids. We highlight a number of specific quantum spin liquid candidate materials and their structure-property relationships, elucidating their fascinating behavior and connecting it to the intricacies of their structures. Furthermore, we share our thoughts on defects and their inevitable presence in materials, of which quantum spin liquids are no exception, which can complicate the interpretation of characterization of these materials, and urge the community to extend their attention to materials preparation and data analysis, cognizant of the impact of defects. This review was written with the intention of providing guidance on improving the materials design and growth of quantum spin liquids, and to paint a picture of the beauty of the underlying chemistry of this exciting class of materials.
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Affiliation(s)
- Juan R Chamorro
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States.,Institute for Quantum Matter, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Tyrel M McQueen
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States.,Institute for Quantum Matter, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, United States.,Department of Materials Science and Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Thao T Tran
- Department of Chemistry, Clemson University, Clemson, South Carolina 29634, United States
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2
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Kundu S, Hossain A, S PK, Das R, Baenitz M, Baker PJ, Orain JC, Joshi DC, Mathieu R, Mahadevan P, Pujari S, Bhattacharjee S, Mahajan AV, Sarma DD. Signatures of a Spin-1/2 Cooperative Paramagnet in the Diluted Triangular Lattice of Y_{2}CuTiO_{6}. PHYSICAL REVIEW LETTERS 2020; 125:117206. [PMID: 32975979 DOI: 10.1103/physrevlett.125.117206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 06/11/2020] [Accepted: 08/04/2020] [Indexed: 06/11/2023]
Abstract
We present a combination of thermodynamic and dynamic experimental signatures of a disorder driven dynamic cooperative paramagnet in a 50% site diluted triangular lattice spin-1/2 system: Y_{2}CuTiO_{6}. Magnetic ordering and spin freezing are absent down to 50 mK, far below the Curie-Weiss scale (-θ_{CW}) of ∼134 K. We observe scaling collapses of the magnetic field and temperature dependent magnetic heat capacity and magnetization data, respectively, in conformity with expectations from the random singlet physics. Our experiments establish the suppression of any freezing scale, if at all present, by more than 3 orders of magnitude, opening a plethora of interesting possibilities such as disorder stabilized long range quantum entangled ground states.
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Affiliation(s)
- S Kundu
- Department of Physics, Indian Institute of Technology, Bombay, Powai, Mumbai 400076, India
| | - Akmal Hossain
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru 560012, India
| | - Pranava Keerthi S
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru 560012, India
| | - Ranjan Das
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru 560012, India
| | - M Baenitz
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - Peter J Baker
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX110QX, United Kingdom
| | | | - D C Joshi
- Department of Engineering Sciences, Uppsala University, Box 534, SE-751 21 Uppsala, Sweden
| | - Roland Mathieu
- Department of Engineering Sciences, Uppsala University, Box 534, SE-751 21 Uppsala, Sweden
| | - Priya Mahadevan
- S. N. Bose National Center for Basic Sciences, Block-JD, Salt Lake, Kolkata-700106, India
| | - Sumiran Pujari
- Department of Physics, Indian Institute of Technology, Bombay, Powai, Mumbai 400076, India
| | - Subhro Bhattacharjee
- International Centre for Theoretical Sciences, Tata Institute of Fundamental Research, Bengaluru 560089, India
| | - A V Mahajan
- Department of Physics, Indian Institute of Technology, Bombay, Powai, Mumbai 400076, India
| | - D D Sarma
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru 560012, India
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3
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Urai M, Miyagawa K, Sasaki T, Taniguchi H, Kanoda K. Quantum Disordering of an Antiferromagnetic Order by Quenched Randomness in an Organic Mott Insulator. PHYSICAL REVIEW LETTERS 2020; 124:117204. [PMID: 32242676 DOI: 10.1103/physrevlett.124.117204] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Accepted: 02/18/2020] [Indexed: 06/11/2023]
Abstract
The behavior of interacting spins subject to randomness is a longstanding issue and the emergence of exotic quantum states is among intriguing theoretical predictions. We show how a quantum-disordered phase emerges from a classical antiferromagnet by controlled randomness. ^{1}H NMR of a successively x-ray-irradiated organic Mott insulator finds that the magnetic order collapses into a spin-glass-like state, immediately after a slight amount of disorder centers are created, and evolves to a gapless quantum-disordered state without spin freezing, spin gap, or critical slowing down, as reported by T. Furukawa et al. [Phys. Rev. Lett. 115, 077001 (2015)]PRLTAO0031-900710.1103/PhysRevLett.115.077001 through sequential reductions in the spin freezing temperature and moment.
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Affiliation(s)
- Mizuki Urai
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
| | - Kazuya Miyagawa
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
| | - Takahiko Sasaki
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - Hiromi Taniguchi
- Department of Physics, Saitama University, Saitama 338-8570, Japan
| | - Kazushi Kanoda
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
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4
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Songvilay M, Rodriguez EE, Lindsay R, Green MA, Walker HC, Rodriguez-Rivera JA, Stock C. Anharmonic Magnon Excitations in Noncollinear and Charge-Ordered RbFe^{2+}Fe^{3+}F_{6}. PHYSICAL REVIEW LETTERS 2018; 121:087201. [PMID: 30192563 DOI: 10.1103/physrevlett.121.087201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 05/10/2018] [Indexed: 06/08/2023]
Abstract
RbFe^{2+}Fe^{3+}F_{6} is an example of a charge ordered antiferromagnet where iron sites, with differing valences, are structurally separated into two interpenetrating sublattices. The low temperature magnetically ordered Fe^{2+} (S=2) and Fe^{3+} (S=5/2) moments form a noncollinear orthogonal structure with the Fe^{3+} site displaying a reduced static ordered moment. Neutron spectroscopy on single crystals finds two distinct spin wave branches with a dominant coupling along the Fe^{3+} chain axis (b axis). High resolution spectroscopic measurements find an intense energy and momentum broadened magnetic band of scattering bracketing a momentum-energy region where two magnon processes are kinematically allowed. These anharmonic excitations are enhanced in this noncollinear magnet owing to the orthogonal spin arrangement.
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Affiliation(s)
- M Songvilay
- School of Physics and Astronomy and Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
| | - E E Rodriguez
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
| | - R Lindsay
- School of Physical Sciences, University of Kent, Canterbury CT2 7NH, United Kingdom
| | - M A Green
- School of Physical Sciences, University of Kent, Canterbury CT2 7NH, United Kingdom
| | - H C Walker
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, United Kingdom
| | - J A Rodriguez-Rivera
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
- Department of Materials Science, University of Maryland, College Park, Maryland 20742, USA
| | - C Stock
- School of Physics and Astronomy and Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
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5
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de Pedro I, Fabelo O, García-Saiz A, Vallcorba O, Junquera J, Blanco JA, Waerenborgh JC, Andreica D, Wildes A, Fernández-Díaz MT, Fernández JR. Dynamically slow solid-to-solid phase transition induced by thermal treatment of DimimFeCl4 magnetic ionic liquid. Phys Chem Chem Phys 2018; 18:21881-92. [PMID: 27439896 DOI: 10.1039/c6cp02433e] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The results reported here represent the first direct experimental observations supporting the existence of a solid-to-solid phase transition induced by thermal treatment in magnetic ionic liquids (MILs). The phase transitions of the solid phases of 1,3-dimethylimidazolium tetrachloroferrate, DimimFeCl4, are closely related to its thermal history. Two series of solid-to-solid phase transitions can be described in this MIL: (i) from room temperature (RT) phase II [space group (s.g.) = P21] to phase I-a [s.g. = P212121] via thermal quenching or via fast cooling at T > 2 K min(-1); (ii) from phase I-a to phase I-b [s.g. = P21/c] when the temperature was kept above 180 K for several minutes. The latter involves a slow translational and reorientational dynamical process of both the imidazolium cation and the tetrachloroferrate anion and has been characterized using synchrotron and neutron powder diffraction and DFT (density functional theory) studies. The transition is also related to the modification of the super-exchange pathways of low-temperature phases which show a overall antiferromagnetic behavior. A combination of several experimental methods such as magnetometry, Mössbauer and muon spectroscopy together with polarized and non-polarized neutron powder diffraction has been used in order to characterize the different features observed in these phases.
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Affiliation(s)
- Imanol de Pedro
- CITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander, Spain.
| | - Oscar Fabelo
- Institut Laue-Langevin, BP 156X, F-38042 Grenoble Cedex, France.
| | - Abel García-Saiz
- CITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander, Spain.
| | - Oriol Vallcorba
- ALBA Synchrotron Light Source, Cerdanyola del Vallés, Barcelona, Spain
| | - Javier Junquera
- CITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander, Spain.
| | | | - João Carlos Waerenborgh
- Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, 2695-066 Bobadela LRS, Portugal
| | - D Andreica
- Faculty of Physics, Babes-Bolyai University, 400084 Cluj-Napoca, Romania
| | - Andrew Wildes
- Institut Laue-Langevin, BP 156X, F-38042 Grenoble Cedex, France.
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6
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Mole RA, Greene S, Henry PF, Humphrey SM, Rule KC, Unruh T, Weldon GF, Yu D, Stride JA, Wood PT. Magnetic Properties of the Distorted Kagomé Lattice Mn 3(1,2,4-(O 2C) 3C 6H 3) 2. Inorg Chem 2017. [DOI: 10.1021/acs.inorgchem.7b00597] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Richard A. Mole
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee
DC, NSW 2225, Australia
- Department
of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia
| | - Stephen Greene
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
| | - Paul F. Henry
- Institut Laue-Langevin, CS 20156, F-38042 Grenoble Cedex 9, France
- The
ISIS
Facility, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, U.K
| | - Simon M. Humphrey
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
- Department
of Chemistry, University of Texas at Austin, Welch Hall 2.204, 105E. 24th Street
A5300, Austin, Texas 78712-1224, United States
| | - Kirrily C. Rule
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee
DC, NSW 2225, Australia
| | - Tobias Unruh
- Heinz
Maier Leibnitz Zenturm, Technische Universitaet Muenchen, Lichtenbergstrasse
1, Garching 85747, Germany
- Chair
for Crystallography and Structural Physics, Physics Department, University of Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Gerald F. Weldon
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
| | - Dehong Yu
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee
DC, NSW 2225, Australia
| | - John A. Stride
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee
DC, NSW 2225, Australia
- Department
of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia
| | - Paul T. Wood
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
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7
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Messio L, Bieri S, Lhuillier C, Bernu B. Chiral Spin Liquid on a Kagome Antiferromagnet Induced by the Dzyaloshinskii-Moriya Interaction. PHYSICAL REVIEW LETTERS 2017; 118:267201. [PMID: 28707912 DOI: 10.1103/physrevlett.118.267201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Indexed: 06/07/2023]
Abstract
The quantum spin liquid material herbertsmithite is described by an antiferromagnetic Heisenberg model on the kagome lattice with a non-negligible Dzyaloshinskii-Moriya interaction (DMI). A well-established phase transition to the q=0 long-range order occurs in this model when the DMI strength increases, but the precise nature of a small-DMI phase remains controversial. Here, we describe a new phase obtained from Schwinger-boson mean-field theory that is stable at small DMI, and which can explain the dispersionless spectrum seen in the inelastic neutron scattering experiment by Han et al. [Nature (London) 492, 406 (2012)NATUAS0028-083610.1038/nature11659]. It is a time-reversal symmetry breaking Z_{2} spin liquid, with the unique property of a small and constant spin gap in an extended region of the Brillouin zone. The phase diagram as a function of DMI and spin size is given, and dynamical spin structure factors are presented.
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Affiliation(s)
- Laura Messio
- Laboratoire de Physique Théorique de la Matière Condensée, CNRS UMR 7600, Université Pierre et Marie Curie, Sorbonne Universités, 75252 Paris, France
| | - Samuel Bieri
- Institute for Theoretical Physics, ETH Zürich, 8099 Zürich, Switzerland
| | - Claire Lhuillier
- Laboratoire de Physique Théorique de la Matière Condensée, CNRS UMR 7600, Université Pierre et Marie Curie, Sorbonne Universités, 75252 Paris, France
| | - Bernard Bernu
- Laboratoire de Physique Théorique de la Matière Condensée, CNRS UMR 7600, Université Pierre et Marie Curie, Sorbonne Universités, 75252 Paris, France
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8
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Sushkov AB, Jenkins GS, Han TH, Lee YS, Drew HD. Infrared phonons as a probe of spin-liquid states in herbertsmithite ZnCu 3(OH) 6Cl 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:095802. [PMID: 28004638 DOI: 10.1088/1361-648x/aa5566] [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
We report on temperature dependence of the infrared reflectivity spectra of a single crystalline herbertsmithite in two polarizations-parallel and perpendicular to the kagome plane of Cu atoms. We observe anomalous broadening of the low frequency phonons possibly caused by fluctuations in the exotic dynamical magnetic order of the spin liquid.
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Affiliation(s)
- A B Sushkov
- Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park, MD 20742, USA
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9
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Zorko A, Herak M, Gomilšek M, van Tol J, Velázquez M, Khuntia P, Bert F, Mendels P. Symmetry Reduction in the Quantum Kagome Antiferromagnet Herbertsmithite. PHYSICAL REVIEW LETTERS 2017; 118:017202. [PMID: 28106444 DOI: 10.1103/physrevlett.118.017202] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Indexed: 06/06/2023]
Abstract
Employing complementary torque magnetometry and electron spin resonance on single crystals of herbertsmithite, the closest realization to date of a quantum kagome antiferromagnet featuring a spin-liquid ground state, we provide novel insight into different contributions to its magnetism. At low temperatures, two distinct types of defects with different magnetic couplings to the kagome spins are found. Surprisingly, their magnetic response contradicts the threefold symmetry of the ideal kagome lattice, suggesting the presence of a global structural distortion that may be related to the establishment of the spin-liquid ground state.
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Affiliation(s)
- A Zorko
- Jožef Stefan Institute, Jamova c. 39, SI-1000 Ljubljana, Slovenia
| | - M Herak
- Institute of Physics, Bijenička c. 46, HR-10000 Zagreb, Croatia
| | - M Gomilšek
- Jožef Stefan Institute, Jamova c. 39, SI-1000 Ljubljana, Slovenia
| | - J van Tol
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - M Velázquez
- CNRS, Université de Bordeaux, ICMCB, UPR 9048, 87 Avenue du Dr. A. Schweitzer, 33608 Pessac Cedex, France
| | - P Khuntia
- Laboratoire de Physique des Solides, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - F Bert
- Laboratoire de Physique des Solides, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - P Mendels
- Laboratoire de Physique des Solides, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France
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10
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Savary L, Balents L. Quantum spin liquids: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:016502. [PMID: 27823986 DOI: 10.1088/0034-4885/80/1/016502] [Citation(s) in RCA: 296] [Impact Index Per Article: 42.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Quantum spin liquids may be considered 'quantum disordered' ground states of spin systems, in which zero-point fluctuations are so strong that they prevent conventional magnetic long-range order. More interestingly, quantum spin liquids are prototypical examples of ground states with massive many-body entanglement, which is of a degree sufficient to render these states distinct phases of matter. Their highly entangled nature imbues quantum spin liquids with unique physical aspects, such as non-local excitations, topological properties, and more. In this review, we discuss the nature of such phases and their properties based on paradigmatic models and general arguments, and introduce theoretical technology such as gauge theory and partons, which are conveniently used in the study of quantum spin liquids. An overview is given of the different types of quantum spin liquids and the models and theories used to describe them. We also provide a guide to the current status of experiments in relation to study quantum spin liquids, and to the diverse probes used therein.
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Affiliation(s)
- Lucile Savary
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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11
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Paddison JAM, Ong HS, Hamp JO, Mukherjee P, Bai X, Tucker MG, Butch NP, Castelnovo C, Mourigal M, Dutton SE. Emergent order in the kagome Ising magnet Dy 3Mg 2Sb 3O 14. Nat Commun 2016; 7:13842. [PMID: 27996012 PMCID: PMC5187434 DOI: 10.1038/ncomms13842] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 11/04/2016] [Indexed: 01/27/2023] Open
Abstract
The Ising model—in which degrees of freedom (spins) are binary valued (up/down)—is a cornerstone of statistical physics that shows rich behaviour when spins occupy a highly frustrated lattice such as kagome. Here we show that the layered Ising magnet Dy3Mg2Sb3O14 hosts an emergent order predicted theoretically for individual kagome layers of in-plane Ising spins. Neutron-scattering and bulk thermomagnetic measurements reveal a phase transition at ∼0.3 K from a disordered spin-ice-like regime to an emergent charge ordered state, in which emergent magnetic charge degrees of freedom exhibit three-dimensional order while spins remain partially disordered. Monte Carlo simulations show that an interplay of inter-layer interactions, spin canting and chemical disorder stabilizes this state. Our results establish Dy3Mg2Sb3O14 as a tuneable system to study interacting emergent charges arising from kagome Ising frustration. Frustration in lattices of interacting spins can lead to rich and exotic physics, such as fractionalized excitations and emergent order. Here, the authors demonstrate a low-temperature transition from a disordered spin-ice-like phase to an emergent charge ordered phase in the bulk kagome Ising magnet Dy3Mg2Sb3O14.
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Affiliation(s)
- Joseph A M Paddison
- Department of Physics, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK.,School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Harapan S Ong
- Department of Physics, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - James O Hamp
- Department of Physics, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Paromita Mukherjee
- Department of Physics, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Xiaojian Bai
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Matthew G Tucker
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, UK.,Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Nicholas P Butch
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Claudio Castelnovo
- Department of Physics, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Martin Mourigal
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - S E Dutton
- Department of Physics, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
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12
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Fu M, Imai T, Han TH, Lee YS. Evidence for a gapped spin-liquid ground state in a kagome Heisenberg antiferromagnet. Science 2015; 350:655-8. [PMID: 26542565 DOI: 10.1126/science.aab2120] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The kagome Heisenberg antiferromagnet is a leading candidate in the search for a spin system with a quantum spin-liquid ground state. The nature of its ground state remains a matter of active debate. We conducted oxygen-17 single-crystal nuclear magnetic resonance (NMR) measurements of the spin-1/2 kagome lattice in herbertsmithite [ZnCu3(OH)6Cl2], which is known to exhibit a spinon continuum in the spin excitation spectrum. We demonstrated that the intrinsic local spin susceptibility χ(kagome), deduced from the oxygen-17 NMR frequency shift, asymptotes to zero below temperatures of 0.03J, where J ~ 200 kelvin is the copper-copper superexchange interaction. Combined with the magnetic field dependence of χ(kagome) that we observed at low temperatures, these results imply that the kagome Heisenberg antiferromagnet has a spin-liquid ground state with a finite gap.
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Affiliation(s)
- Mingxuan Fu
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S4M1, Canada
| | - Takashi Imai
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S4M1, Canada. Canadian Institute for Advanced Research, Toronto, Ontario M5G1Z8, Canada
| | - Tian-Heng Han
- James Franck Institute and Department of Physics, University of Chicago, Chicago, IL 60637, USA. Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Young S Lee
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. Department of Applied Physics and Department of Photon Science, Stanford University and SLAC National Accelerator Laboratory, Stanford, CA 94305, USA
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13
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Clark L, Aidoudi FH, Black C, Arachchige KSA, Slawin AMZ, Morris RE, Lightfoot P. Extending the Family of V4+S=${{ 1/2 }}$ Kagome Antiferromagnets. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201506869] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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14
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Clark L, Aidoudi FH, Black C, Arachchige KSA, Slawin AMZ, Morris RE, Lightfoot P. Extending the Family of V(4+) S=(1/2) Kagome Antiferromagnets. Angew Chem Int Ed Engl 2015; 54:15457-61. [PMID: 26515792 DOI: 10.1002/anie.201506869] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 09/28/2015] [Indexed: 11/06/2022]
Abstract
The ionothermal synthesis, structure, and magnetic susceptibility of a novel inorganic-organic hybrid material, imidazolium vanadium(III,IV) oxyfluoride [C3 H5 N2 ][V9 O6 F24 (H2 O)2 ] (ImVOF) are presented. The structure consists of inorganic vanadium oxyfluoride slabs with kagome layers of V(4+) S=${{ 1/2 }}$ ions separated by a mixed valence layer. These inorganic slabs are intercalated with imidazolium cations. Quinuclidinium (Q) and pyrazinium (Pyz) cations can also be incorporated into the hybrid structure type to give QVOF and PyzVOF analogues, respectively. The highly frustrated topology of the inorganic slabs, along with the quantum nature of the magnetism associated with V(4+) , means that these materials are excellent candidates to host exotic magnetic ground states, such as the highly sought quantum spin liquid. Magnetic susceptibility measurements of all samples suggest an absence of conventional long-range magnetic order down to 2 K despite considerable antiferromagnetic exchange.
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Affiliation(s)
- Lucy Clark
- School of Chemistry and EaStChem, University of St Andrews, St Andrews, Fife, KY16 9ST (UK)
| | - Farida H Aidoudi
- School of Chemistry and EaStChem, University of St Andrews, St Andrews, Fife, KY16 9ST (UK)
| | - Cameron Black
- School of Chemistry and EaStChem, University of St Andrews, St Andrews, Fife, KY16 9ST (UK)
| | - Kasun S A Arachchige
- School of Chemistry and EaStChem, University of St Andrews, St Andrews, Fife, KY16 9ST (UK)
| | - Alexandra M Z Slawin
- School of Chemistry and EaStChem, University of St Andrews, St Andrews, Fife, KY16 9ST (UK)
| | - Russell E Morris
- School of Chemistry and EaStChem, University of St Andrews, St Andrews, Fife, KY16 9ST (UK)
| | - Philip Lightfoot
- School of Chemistry and EaStChem, University of St Andrews, St Andrews, Fife, KY16 9ST (UK).
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15
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Ralko A, Rousochatzakis I. Resonating-Valence-Bond Physics Is Not Always Governed by the Shortest Tunneling Loops. PHYSICAL REVIEW LETTERS 2015; 115:167202. [PMID: 26550898 DOI: 10.1103/physrevlett.115.167202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Indexed: 06/05/2023]
Abstract
It is well known that the low-energy sector of quantum spin liquids and other magnetically disordered systems is governed by short-ranged resonating-valence bonds. Here we show that the standard minimal truncation to the nearest-neighbor valence-bond basis fails completely even for systems where it should work the most, according to received wisdom. This paradigm shift is demonstrated for the quantum spin-1/2 square kagome, where strong geometric frustration, similar to the kagome, prevents magnetic ordering down to zero temperature. The shortest tunneling events bear the strongest longer-range singlet fluctuations, leading to amplitudes that do not drop exponentially with the length of the loop L, and to an unexpected loop-six valence-bond crystal, which is otherwise very high in energy at the minimal truncation level. The low-energy effective description gives in addition a clear example of correlated loop processes that depend not only on the type of the loop but also on its lattice embedding, a direct manifestation of the long-range nature of the virtual singlets.
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Affiliation(s)
- Arnaud Ralko
- Institut Néel, UPR2940, Université Grenoble Alpes et CNRS, Grenoble FR-38042, France
| | - Ioannis Rousochatzakis
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55116, USA
- Max Planck Institut für Physik Komplexer Systeme, Nöthnitzer Strasse 38, 01187 Dresden, Germany
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16
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Sibille R, Lhotel E, Pomjakushin V, Baines C, Fennell T, Kenzelmann M. Candidate Quantum Spin Liquid in the Ce3+ Pyrochlore Stannate Ce2Sn2O7. PHYSICAL REVIEW LETTERS 2015; 115:097202. [PMID: 26371677 DOI: 10.1103/physrevlett.115.097202] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Indexed: 06/05/2023]
Abstract
We report the low-temperature magnetic properties of Ce2Sn2O7, a rare-earth pyrochlore. Our susceptibility and magnetization measurements show that due to the thermal isolation of a Kramers doublet ground state, Ce2Sn2O7 has Ising-like magnetic moments of ∼1.18 μ_{B}. The magnetic moments are confined to the local trigonal axes, as in a spin ice, but the exchange interactions are antiferromagnetic. Below 1 K, the system enters a regime with antiferromagnetic correlations. In contrast to predictions for classical ⟨111⟩-Ising spins on the pyrochlore lattice, there is no sign of long-range ordering down to 0.02 K. Our results suggest that Ce2Sn2O7 features an antiferromagnetic liquid ground state with strong quantum fluctuations.
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Affiliation(s)
- Romain Sibille
- Laboratory for Scientific Developments and Novel Materials, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Elsa Lhotel
- Institut Néel, CNRS, and Université Joseph Fourier, BP 166, 38042 Grenoble Cedex 9, France
| | - Vladimir Pomjakushin
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Chris Baines
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Tom Fennell
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Michel Kenzelmann
- Laboratory for Scientific Developments and Novel Materials, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
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17
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Ehlers G, Stewart J, Deen P, Andersen K. Neutronxyz– polarization analysis at a time-of-flight instrument. EPJ WEB OF CONFERENCES 2015. [DOI: 10.1051/epjconf/20158303004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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18
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Clark L, Nilsen GJ, Kermarrec E, Ehlers G, Knight KS, Harrison A, Attfield JP, Gaulin BD. From spin glass to quantum spin liquid ground states in molybdate pyrochlores. PHYSICAL REVIEW LETTERS 2014; 113:117201. [PMID: 25260001 DOI: 10.1103/physrevlett.113.117201] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Indexed: 06/03/2023]
Abstract
We present new magnetic heat capacity and neutron scattering results for two magnetically frustrated molybdate pyrochlores: S=1 oxide Lu_{2}Mo_{2}O_{7} and S=1/2 oxynitride Lu_{2}Mo_{2}O_{5}N_{2}. Lu_{2}Mo_{2}O_{7} undergoes a transition to an unconventional spin glass ground state at T_{f}∼16 K. However, the preparation of the corresponding oxynitride tunes the nature of the ground state from spin glass to quantum spin liquid. The comparison of the static and dynamic spin correlations within the oxide and oxynitride phases presented here reveals the crucial role played by quantum fluctuations in the selection of a ground state. Furthermore, we estimate an upper limit for a gap in the spin excitation spectrum of the quantum spin liquid state of the oxynitride of Δ∼0.05 meV or Δ/|θ|∼0.004, in units of its antiferromagnetic Weiss constant θ∼-121 K.
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Affiliation(s)
- L Clark
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - G J Nilsen
- Institute Laue-Langevin, 6 Rue Jules Horowitz, 38042 Grenoble, France
| | - E Kermarrec
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - G Ehlers
- Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - K S Knight
- ISIS Facility, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - A Harrison
- CSEC and School of Chemistry, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JZ, United Kingdom and Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - J P Attfield
- CSEC and School of Chemistry, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JZ, United Kingdom
| | - B D Gaulin
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada and Brockhouse Institute for Materials Research, Hamilton, Ontario L8S 4M1, Canada and Canadian Institute for Advanced Research, 180 Dundas Street West, Toronto, Ontario M5G 1Z8, Canada
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19
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Landee CP, Turnbull MM. Review: A gentle introduction to magnetism: units, fields, theory, and experiment. J COORD CHEM 2014. [DOI: 10.1080/00958972.2014.889294] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Christopher P. Landee
- Department of Physics and Carlson School of Chemistry and Biochemistry, Clark University, Worcester, MA, USA
| | - Mark M. Turnbull
- Department of Physics and Carlson School of Chemistry and Biochemistry, Clark University, Worcester, MA, USA
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20
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Mourigal M, Fuhrman WT, Sheckelton JP, Wartelle A, Rodriguez-Rivera JA, Abernathy DL, McQueen TM, Broholm CL. Molecular quantum magnetism in LiZn2Mo3O8. PHYSICAL REVIEW LETTERS 2014; 112:027202. [PMID: 24484043 DOI: 10.1103/physrevlett.112.027202] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Indexed: 06/03/2023]
Abstract
Inelastic neutron scattering at low temperatures T≤30 K from a powder of LiZn2Mo3O8 demonstrates this triangular-lattice antiferromagnet hosts collective magnetic excitations from spin-1/2 Mo3O13 molecules. Apparently gapless (Δ<0.2 meV) and extending at least up to 2.5 meV, the low-energy magnetic scattering cross section is surprisingly broad in momentum space and involves one-third of the spins present above 100 K. The data are compatible with the presence of valence bonds involving nearest-neighbor and next-nearest-neighbor spins forming a disordered or dynamic state.
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Affiliation(s)
- M Mourigal
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - W T Fuhrman
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - J P Sheckelton
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA and Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - A Wartelle
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA and École Normale Supérieure de Lyon, Université de Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France
| | - J A Rodriguez-Rivera
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA and Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
| | - D L Abernathy
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6475, USA
| | - T M McQueen
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA and Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - C L Broholm
- Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA and NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA and Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6475, USA
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21
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Aidoudi FH, Downie LJ, Morris RE, A. de Vries M, Lightfoot P. A hybrid vanadium fluoride with structurally isolated S = 1 kagome layers. Dalton Trans 2014; 43:6304-7. [DOI: 10.1039/c4dt00452c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel hybrid vanadium fluoride displaying isolated S = 1 kagome layers separated by ammonium and ethylammonium cations is prepared; this compound shows interesting magnetic properties.
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Affiliation(s)
| | - Lewis J. Downie
- EaStChem
- School of Chemistry
- University of St Andrews
- St Andrews, UK
| | | | | | - Philip Lightfoot
- EaStChem
- School of Chemistry
- University of St Andrews
- St Andrews, UK
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22
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Paddison JAM, Stewart JR, Goodwin AL. SPINVERT: a program for refinement of paramagnetic diffuse scattering data. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:454220. [PMID: 24140881 DOI: 10.1088/0953-8984/25/45/454220] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We present a program (spinvert; http://spinvert.chem.ox.ac.uk) for refinement of magnetic diffuse scattering data for frustrated magnets, spin liquids, spin glasses, and other magnetically disordered materials. The approach uses reverse Monte Carlo refinement to fit a large configuration of spins to experimental powder neutron diffraction data. Despite fitting to spherically averaged data, this approach allows the recovery of the three-dimensional magnetic diffuse scattering pattern and the spin-pair correlation function. We illustrate the use of the spinvert program with two case studies. First, we use simulated powder data for the canonical antiferromagnetic Heisenberg model on the kagome lattice to discuss the sensitivity of spinvert refinement to both pairwise and higher-order spin correlations. The effect of limited experimental data on the results is also considered. Second, we re-analyse published experimental data on the frustrated system Y0.5Ca0.5BaCo4O7. The results from spinvert refinement indicate similarities between Y0.5Ca0.5BaCo4O7 and its parent compound YBaCo4O7, which were overlooked in previous analyses using powder data.
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Affiliation(s)
- Joseph A M Paddison
- Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, UK. ISIS Facility, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX, UK
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23
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Calder S, Giblin SR, Parker DR, Deen PP, Ritter C, Stewart JR, Rols S, Fennell T. Neutron scattering and μSR investigations of the low temperature state of LuCuGaO₄. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:356002. [PMID: 23917326 DOI: 10.1088/0953-8984/25/35/356002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
LuCuGaO₄ has magnetic Cu(2+) and diamagnetic Ga(3+) ions distributed on a triangular bilayer and is suggested to undergo a spin glass transition at Tg ∼ 0.4 K. Using μSR (muon spin rotation) and neutron scattering measurements, we show that at low temperature the spins form a short range correlated state with spin fluctuations detectable over a wide range of timescales: at 0.05 K magnetic fluctuations can be detected in both the μSR time window and also extending beyond 7 meV in the inelastic neutron scattering response, indicating magnetic fluctuations spanning timescales between ∼10(-5) and ∼10(-10) s. The dynamical susceptibility scales according to the form χ″(ω)T(α), with α = 1, throughout the measured temperature range (0.05-50 K). These effects are associated with quantum fluctuations and some degree of structural disorder in ostensibly quite different materials, including certain heavy fermion alloys, kagome spin liquids, quantum spin glasses, and valence bond glasses. We therefore suggest that LuCuGaO₄ is an interesting model compound for the further examination of disorder and quantum magnetism.
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Affiliation(s)
- S Calder
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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24
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Clark L, Orain JC, Bert F, De Vries MA, Aidoudi FH, Morris RE, Lightfoot P, Lord JS, Telling MTF, Bonville P, Attfield JP, Mendels P, Harrison A. Gapless spin liquid ground state in the S = 1/2 vanadium oxyfluoride kagome antiferromagnet [NH4]2[C7H14N][V7O6F18]. PHYSICAL REVIEW LETTERS 2013; 110:207208. [PMID: 25167449 DOI: 10.1103/physrevlett.110.207208] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Indexed: 06/03/2023]
Abstract
The vanadium oxyfluoride [NH(4)](2)[C(7)H(14)N][V(7)O(6)F(18)] (DQVOF) is a geometrically frustrated magnetic bilayer material. The structure consists of S = 1/2 kagome planes of V(4+) d(1) ions with S = 1 V(3+) d(2) ions located between the kagome layers. Muon spin relaxation measurements demonstrate the absence of spin freezing down to 40 mK despite an energy scale of 60 K for antiferromagnetic exchange interactions. From magnetization and heat capacity measurements we conclude that the S = 1 spins of the interplane V(3+) ions are weakly coupled to the kagome layers, such that DQVOF can be viewed as an experimental model for S = 1/2 kagome physics, and that it displays a gapless spin liquid ground state.
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Affiliation(s)
- L Clark
- CSEC and School of Chemistry, The University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom
| | - J C Orain
- Laboratoire de Physique des Solides, UMR CNRS, Université Paris-Sud, 91504 Orsay, France
| | - F Bert
- Laboratoire de Physique des Solides, UMR CNRS, Université Paris-Sud, 91504 Orsay, France
| | - M A De Vries
- CSEC and School of Chemistry, The University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom
| | - F H Aidoudi
- School of Chemistry and EaSTChem, University of St. Andrews, St. Andrews KY16 9ST, United Kingdom
| | - R E Morris
- School of Chemistry and EaSTChem, University of St. Andrews, St. Andrews KY16 9ST, United Kingdom
| | - P Lightfoot
- School of Chemistry and EaSTChem, University of St. Andrews, St. Andrews KY16 9ST, United Kingdom
| | - J S Lord
- ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX110QX, United Kingdom
| | - M T F Telling
- ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX110QX, United Kingdom and Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
| | - P Bonville
- Service de Physique de l'État Condensé, CEA-CNRS, CE-Saclay, F-91191 Gif-Sur-Yvette, France
| | - J P Attfield
- CSEC and School of Chemistry, The University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom
| | - P Mendels
- Laboratoire de Physique des Solides, UMR CNRS, Université Paris-Sud, 91504 Orsay, France and Institut Universitaire de France, 103 bd Saint Michel, F-75005 Paris, France
| | - A Harrison
- CSEC and School of Chemistry, The University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom and Institut Laue Langevin, 6 Rue Jules Horowitz, 38042 Grenoble Cedex 9, France
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25
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Nilsen GJ, de Vries MA, Stewart JR, Harrison A, Rønnow HM. Low-energy spin dynamics of the s = 1/2 kagome system herbertsmithite. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:106001. [PMID: 23388841 DOI: 10.1088/0953-8984/25/10/106001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The low-energy (ε = ħω < 1 meV), low-temperature (T = 0.05 K) spin dynamics of the s = 1/2 kagome candidate herbertsmithite are probed in the presence of magnetic fields up to 2.5 T. The zero-field spectra reveal a very weak continuum of scattering at T = 10 K and a broad inelastic peak centred at ε(max) = 0.2 meV at lower temperatures, T < 1 K. The broad peak is found to be strongly damped, with a liquid-like structure factor implying correlations at length scales up to r = 6 Å. The field dependence of the peak appears to follow the Zeeman splitting of s = 1/2 excitations, consistent with the weakly split 'doublets' observed in low-temperature specific heat. A possible explanation of these observations is a short-range correlated state involving defect spins between the kagome planes and moments in the kagome layers.
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Affiliation(s)
- G J Nilsen
- Institut Laue-Langevin, 6 rue Jules Horowitz, F-38042 Grenoble, France.
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26
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Fractionalized excitations in the spin-liquid state of a kagome-lattice antiferromagnet. Nature 2013; 492:406-10. [PMID: 23257883 DOI: 10.1038/nature11659] [Citation(s) in RCA: 262] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2012] [Accepted: 10/02/2012] [Indexed: 11/08/2022]
Abstract
The experimental realization of quantum spin liquids is a long-sought goal in physics, as they represent new states of matter. Quantum spin liquids cannot be described by the broken symmetries associated with conventional ground states. In fact, the interacting magnetic moments in these systems do not order, but are highly entangled with one another over long ranges. Spin liquids have a prominent role in theories describing high-transition-temperature superconductors, and the topological properties of these states may have applications in quantum information. A key feature of spin liquids is that they support exotic spin excitations carrying fractional quantum numbers. However, detailed measurements of these 'fractionalized excitations' have been lacking. Here we report neutron scattering measurements on single-crystal samples of the spin-1/2 kagome-lattice antiferromagnet ZnCu(3)(OD)(6)Cl(2) (also called herbertsmithite), which provide striking evidence for this characteristic feature of spin liquids. At low temperatures, we find that the spin excitations form a continuum, in contrast to the conventional spin waves expected in ordered antiferromagnets. The observation of such a continuum is noteworthy because, so far, this signature of fractional spin excitations has been observed only in one-dimensional systems. The results also serve as a hallmark of the quantum spin-liquid state in herbertsmithite.
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27
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Fåk B, Kermarrec E, Messio L, Bernu B, Lhuillier C, Bert F, Mendels P, Koteswararao B, Bouquet F, Ollivier J, Hillier AD, Amato A, Colman RH, Wills AS. Kapellasite: a kagome quantum spin liquid with competing interactions. PHYSICAL REVIEW LETTERS 2012; 109:037208. [PMID: 22861895 DOI: 10.1103/physrevlett.109.037208] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 05/09/2012] [Indexed: 06/01/2023]
Abstract
Magnetic susceptibility, NMR, muon spin relaxation, and inelastic neutron scattering measurements show that kapellasite, Cu3Zn(OH)6Cl2, a geometrically frustrated spin-1/2 kagome antiferromagnet polymorphic with herbertsmithite, is a gapless spin liquid showing unusual dynamic short-range correlations of noncoplanar cuboc2 type which persist down to 20 mK. The Hamiltonian is determined from a fit of a high-temperature series expansion to bulk susceptibility data and possesses competing exchange interactions. The magnetic specific heat calculated from these exchange couplings is in good agreement with experiment. The temperature dependence of the magnetic structure factor and the muon relaxation rate are calculated in a Schwinger-boson approach and compared to experimental results.
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Affiliation(s)
- B Fåk
- SPSMS, UMR-E CEA/UJF-Grenoble-1, INAC, F-38054 Grenoble Cedex 9, France
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28
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Chen YH, Tao HS, Yao DX, Liu WM. Kondo metal and ferrimagnetic insulator on the triangular kagome lattice. PHYSICAL REVIEW LETTERS 2012; 108:246402. [PMID: 23004298 DOI: 10.1103/physrevlett.108.246402] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Indexed: 06/01/2023]
Abstract
We obtain the rich phase diagrams in the Hubbard model on the triangular kagome lattice as a function of interaction, temperature, and asymmetry by combining the cellular dynamical mean-field theory with the continuous time quantum Monte Carlo method. The phase diagrams show the asymmetry separates the critical points in the Mott transition of two sublattices on the triangular kagome lattice and produces two novel phases called plaquette insulator with a clearly visible gap and a gapless Kondo metal. When the Coulomb interaction is stronger than the critical value U(c), a short range paramagnetic insulating state, which is a candidate for the short rang resonating valence-bond spin liquid, emerges before the ferrimagnetic order is formed independent of asymmetry. Furthermore, we discuss how to measure these phases in future experiments.
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Affiliation(s)
- Yao-Hua Chen
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
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29
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Kozlenko DP, Kusmartseva AF, Lukin EV, Keen DA, Marshall WG, de Vries MA, Kamenev KV. From quantum disorder to magnetic order in an s=1/2 kagome lattice: a structural and magnetic study of herbertsmithite at high pressure. PHYSICAL REVIEW LETTERS 2012; 108:187207. [PMID: 22681115 DOI: 10.1103/physrevlett.108.187207] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Indexed: 06/01/2023]
Abstract
The structural and magnetic properties of deuterated herbertsmithite have been studied by means of neutron powder diffraction and magnetic susceptibility measurements in a wide range of temperatures and pressures. The experimental data demonstrate that a phase transition from the quantum-disordered spin-liquid phase to the long-range ordered antiferromagnetic phase with the Néel temperature T(N)=6 K is induced at P=2.5 GPa. The observed decrease of T(N) upon compression correlates with the anomalies in pressure behavior of Cu-O bond length and Cu-O-Cu bond angles. The reasons for the observed spin-freezing transition are discussed within the framework of the available theoretical models and the recent observation of the field-induced spin freezing.
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Affiliation(s)
- D P Kozlenko
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, 141980 Dubna, Russia
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30
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Jeong M, Bert F, Mendels P, Duc F, Trombe JC, de Vries MA, Harrison A. Field-induced freezing of a quantum spin liquid on the kagome lattice. PHYSICAL REVIEW LETTERS 2011; 107:237201. [PMID: 22182120 DOI: 10.1103/physrevlett.107.237201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 09/06/2011] [Indexed: 05/31/2023]
Abstract
We report (17)O NMR measurements in the S=1/2 (Cu(2+)) kagome antiferromagnet Herbertsmithite ZnCu(3)(OH)(6)Cl(2) down to 45 mK in magnetic fields ranging from 2 to 12 T. While Herbertsmithite displays a gapless spin-liquid behavior in zero field, we uncover an instability toward a spin-solid phase at sub-Kelvin temperature induced by an applied magnetic field. The latter phase shows largely suppressed moments ≲0.1 μ(B) and gapped excitations. The H-T phase diagram suggests the existence of a quantum critical point at the small but finite magnetic field μ(0)H(c)=1.55(25) T. We discuss this finding in light of the perturbative Dzyaloshinskii-Moriya interaction which was theoretically proposed to sustain a quantum critical regime for the quantum kagome Heisenberg antiferromagnet model.
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Affiliation(s)
- M Jeong
- Laboratoire de Physique des Solides, Université Paris-Sud 11, UMR CNRS 8502, 91405 Orsay, France
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31
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Fennell T, Piatek JO, Stephenson RA, Nilsen GJ, Rønnow HM. Spangolite: an s = 1/2 maple leaf lattice antiferromagnet? JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:164201. [PMID: 21471624 DOI: 10.1088/0953-8984/23/16/164201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Spangolite, Cu(6)Al(SO(4))(OH)(12)Cl·3H(2)O, is a hydrated layered copper sulfate mineral. The Cu(2+) ions of each layer form a systematically depleted triangular lattice which approximates a maple leaf lattice. We present details of the crystal structure, which suggest that in spangolite this lattice actually comprises two species of edge linked trimers with different exchange parameters. However, magnetic susceptibility measurements show that despite the structural trimers, the magnetic properties are dominated by dimerization. The high temperature magnetic moment is strongly reduced below that expected for the six s = 1/2 in the unit cell.
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Affiliation(s)
- T Fennell
- Institut Laue Langevin, BP 156, 6, rue Jules Horowitz, 38042, Grenoble Cedex 9, France.
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32
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Singh RRP. Valence bond glass phase in dilute kagome antiferromagnets. PHYSICAL REVIEW LETTERS 2010; 104:177203. [PMID: 20482135 DOI: 10.1103/physrevlett.104.177203] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Revised: 04/02/2010] [Indexed: 05/29/2023]
Abstract
We present a theory for site dilution in the kagome lattice Heisenberg model. The presence of an empty site leads to strong singlet bonds opposite to the impurity. It also creates a free spin which delocalizes near the impurity. Finite impurity concentration leads to a valence bond glass phase with no spin gap, large spin susceptibilities, linear specific heat due to two-level systems, as well as singlet and triplet excitations that decompose into kink-antikink pairs. It provides a framework for a comprehensive understanding of thermodynamic, neutron, and Raman measurements in the herbertsmithite material ZnCu3(OH)6Cl2, including recently reported H/T and omega/T scaling.
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Affiliation(s)
- R R P Singh
- University of California Davis, Davis, California 95616, USA
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Helton JS, Matan K, Shores MP, Nytko EA, Bartlett BM, Qiu Y, Nocera DG, Lee YS. Dynamic scaling in the susceptibility of the spin-1/2 kagome lattice antiferromagnet herbertsmithite. PHYSICAL REVIEW LETTERS 2010; 104:147201. [PMID: 20481955 DOI: 10.1103/physrevlett.104.147201] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Revised: 03/11/2010] [Indexed: 05/29/2023]
Abstract
The spin-1/2 kagome lattice antiferromagnet herbertsmithite, ZnCu(3)(OH)(6)Cl(2), is a candidate material for a quantum spin liquid ground state. We show that the magnetic response of this material displays an unusual scaling relation in both the bulk ac susceptibility and the low energy dynamic susceptibility as measured by inelastic neutron scattering. The quantity chiT(alpha) with alpha approximately 0.66 can be expressed as a universal function of H/T or omega/T. This scaling is discussed in relation to similar behavior seen in systems influenced by disorder or by the proximity to a quantum critical point.
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Affiliation(s)
- J S Helton
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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