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Foury-Leylekian P, Ilakovac V, Fertey P, Baledent V, Milat O, Miyagawa K, Kanoda K, Hiramatsu T, Yoshida Y, Saito G, Alemany P, Canadell E, Tomic S, Pouget JP. New insights into the structural properties of κ-(BEDT-TTF) 2Ag 2(CN) 3 spin liquid. ACTA CRYSTALLOGRAPHICA SECTION B, STRUCTURAL SCIENCE, CRYSTAL ENGINEERING AND MATERIALS 2020; 76:581-590. [PMID: 32831277 DOI: 10.1107/s2052520620005545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 04/20/2020] [Indexed: 06/11/2023]
Abstract
Here, the first accurate study is presented of the room-temperature and 100 K structures of one of the first organic spin liquids, κ-(BEDT-TTF)2Ag2(CN)3. It is shown that the monoclinic structure determined previously is only the average one. It is shown that the exact structure presents triclinic symmetry with two non-equivalent dimers in the unit cell. But surprisingly this does not lead to a sizeable charge disproportionation between dimers. The difference from the analogue compound κ-(BEDT-TTF)2Cu2(CN)3 which also presents a spin liquid phase is discussed in detail. The data provided here show the importance of the anionic layer and in particular the transition metal position in the process of symmetry breaking. The possible impact of the symmetry breaking, albeit weak, on the spin-liquid mechanism and the influence of various disorders on the physical properties of this system is also discussed.
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Affiliation(s)
| | - Vita Ilakovac
- Sorbonne University, UPMC, LCP-MR, CNRS UMR 7614, Paris, F-75252, France
| | - Pierre Fertey
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, Gif-sur-Yvette, F-91192, France
| | - Victor Baledent
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, 91405, Orsay, France
| | - Ognjen Milat
- Institute of Physics, Bijenička cesta 46, Zagreb, HR-10000, Croatia
| | - Kazuya Miyagawa
- Department of Applied Physics, University of Tokyo, Tokyo, 113-8656, Japan
| | - Kazushi Kanoda
- Department of Applied Physics, University of Tokyo, Tokyo, 113-8656, Japan
| | | | - Yukihiro Yoshida
- Faculty of Agriculture, Meijo University, Nagoya, 468-8502, Japan
| | - Gunzi Saito
- Faculty of Agriculture, Meijo University, Nagoya, 468-8502, Japan
| | - Pere Alemany
- Departament de Ciència de Materials i Química Física and Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, Martí i Franquès 1, Barcelona, 08028, Spain
| | - Enric Canadell
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, Bellaterra, 08193, Spain
| | - Silvia Tomic
- Institute of Physics, Bijenička cesta 46, Zagreb, HR-10000, Croatia
| | - Jean Paul Pouget
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, 91405, Orsay, France
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Thermodynamic, Dynamic, and Transport Properties of Quantum Spin Liquid in Herbertsmithite from an Experimental and Theoretical Point of View. CONDENSED MATTER 2019. [DOI: 10.3390/condmat4030075] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In our review, we focus on the quantum spin liquid (QSL), defining the thermodynamic, transport, and relaxation properties of geometrically frustrated magnet (insulators) represented by herbertsmithite ZnCu 3 ( OH ) 6 Cl 2 . The review mostly deals with an historical perspective of our theoretical contributions on this subject, based on the theory of fermion condensation closely related to the emergence (due to geometrical frustration) of dispersionless parts in the fermionic quasiparticle spectrum, so-called flat bands. QSL is a quantum state of matter having neither magnetic order nor gapped excitations even at zero temperature. QSL along with heavy fermion metals can form a new state of matter induced by the topological fermion condensation quantum phase transition. The observation of QSL in actual materials such as herbertsmithite is of fundamental significance both theoretically and technologically, as it could open a path to the creation of topologically protected states for quantum information processing and quantum computation. It is therefore of great importance to establish the presence of a gapless QSL state in one of the most prospective materials, herbertsmithite. In this respect, the interpretation of current theoretical and experimental studies of herbertsmithite are controversial in their implications. Based on published experimental data augmented by our theoretical analysis, we present evidence for the the existence of a QSL in the geometrically frustrated insulator herbertsmithite ZnCu 3 ( OH ) 6 Cl 2 , providing a strategy for unambiguous identification of such a state in other materials. To clarify the nature of QSL in herbertsmithite, we recommend measurements of heat transport, low-energy inelastic neutron scattering, and optical conductivity σ ¯ in ZnCu 3 ( OH ) 6 Cl 2 crystals subject to an external magnetic field at low temperatures. Our analysis of the behavior of σ ¯ in herbertsmithite justifies this set of measurements, which can provide a conclusive experimental demonstration of the nature of its spinon-composed quantum spin liquid. Theoretical study of the optical conductivity of herbertsmithite allows us to expose the physical mechanisms responsible for its temperature and magnetic field dependence. We also suggest that artificially or spontaneously introducing inhomogeneity at nanoscale into ZnCu 3 ( OH ) 6 Cl 2 can both stabilize its QSL and simplify its chemical preparation, and can provide for tests that elucidate the role of impurities. We make predictions of the results of specified measurements related to the dynamical, thermodynamic, and transport properties in the case of a gapless QSL.
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Abstract
Crystalline conductors and superconductors based on organic molecules are a rapidly progressing field of solid-state science, involving chemists, and experimental and theoretical physicists from all around the world[...]
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Pustogow A, Saito Y, Zhukova E, Gorshunov B, Kato R, Lee TH, Fratini S, Dobrosavljević V, Dressel M. Low-Energy Excitations in Quantum Spin Liquids Identified by Optical Spectroscopy. PHYSICAL REVIEW LETTERS 2018; 121:056402. [PMID: 30118313 DOI: 10.1103/physrevlett.121.056402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Indexed: 06/08/2023]
Abstract
The electrodynamic response of organic spin liquids with highly frustrated triangular lattices has been measured in a wide energy range. While the overall optical spectra of these Mott insulators are governed by transitions between the Hubbard bands, distinct in-gap excitations can be identified at low temperatures and frequencies, which we attribute to the quantum-spin-liquid state. For the strongly correlated β^{'}-EtMe_{3}Sb[Pd(dmit)_{2}]_{2}, we discover enhanced conductivity below 175 cm^{-1}, comparable to the energy of the magnetic coupling J≈250 K. For ω→0, these low-frequency excitations vanish faster than the charge-carrier response subject to Mott-Hubbard correlations, resulting in a dome-shaped band peaked at 100 cm^{-1}. Possible relations to spinons, magnons, and disorder are discussed.
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Affiliation(s)
- A Pustogow
- 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany
| | - Y Saito
- 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany
- Department of Physics, Hokkaido University, Sapporo 060-0810, Japan
| | - E Zhukova
- Moscow Institute of Physics and Technology (State University), 141700, Dolgoprudny, Moscow Region, Russia
| | - B Gorshunov
- Moscow Institute of Physics and Technology (State University), 141700, Dolgoprudny, Moscow Region, Russia
| | - R Kato
- Condensed Molecular Materials Laboratory, RIKEN, Wako-shi, Saitama 351-0198, Japan
| | - T-H Lee
- Department of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, USA
| | - S Fratini
- Institut Néel-CNRS and Université Grenoble Alpes, 38042 Grenoble Cedex 9, France
| | - V Dobrosavljević
- Department of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, USA
| | - M Dressel
- 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany
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