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Title: Strong quantum fluctuations in a quantum spin liquid candidate with a Co-based triangular lattice

Abstract

Currently under active study in condensed matter physics, both theoretically and experimentally, are quantum spin liquid (QSL) states, in which no long-range magnetic ordering appears at low temperatures due to strong quantum fluctuations of the magnetic moments. The existing QSL candidates all have their intrinsic disadvantages, however, and solid evidence for quantum fluctuations is scarce. Here, we report a previously unreported compound, N a 2 B a C o ( P O 4 ) 2 , a geometrically frustrated system with effective spin-1/2 local moments for Co 2+ ions on an isotropic 2-dimensional (2D) triangular lattice. Magnetic susceptibility and neutron scattering experiments show no magnetic ordering down to 0.05 K. Thermodynamic measurements show that there is a tremendous amount of magnetic entropy present below 1 K in 0-applied magnetic field. The presence of localized low-energy spin fluctuations is revealed by inelastic neutron measurements. At low applied fields, these spin excitations are confined to low energy and contribute to the anomalously large specific heat. In larger applied fields, the system reverts to normal behavior as evident by both neutron and thermodynamic results. Our experimental characterization thus reveals that this material is an excellent candidate for the experimental realization of a QSL state.

Authors:
; ; ; ;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1564522
Grant/Contract Number:  
SC0019331
Resource Type:
Published Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Volume: 116 Journal Issue: 29; Journal ID: ISSN 0027-8424
Publisher:
Proceedings of the National Academy of Sciences
Country of Publication:
United States
Language:
English

Citation Formats

Zhong, Ruidan, Guo, Shu, Xu, Guangyong, Xu, Zhijun, and Cava, Robert J. Strong quantum fluctuations in a quantum spin liquid candidate with a Co-based triangular lattice. United States: N. p., 2019. Web. doi:10.1073/pnas.1906483116.
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Zhong, Ruidan, Guo, Shu, Xu, Guangyong, Xu, Zhijun, & Cava, Robert J. Strong quantum fluctuations in a quantum spin liquid candidate with a Co-based triangular lattice. United States. doi:10.1073/pnas.1906483116.
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Zhong, Ruidan, Guo, Shu, Xu, Guangyong, Xu, Zhijun, and Cava, Robert J. Tue . "Strong quantum fluctuations in a quantum spin liquid candidate with a Co-based triangular lattice". United States. doi:10.1073/pnas.1906483116.
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@article{osti_1564522,
title = {Strong quantum fluctuations in a quantum spin liquid candidate with a Co-based triangular lattice},
author = {Zhong, Ruidan and Guo, Shu and Xu, Guangyong and Xu, Zhijun and Cava, Robert J.},
abstractNote = {Currently under active study in condensed matter physics, both theoretically and experimentally, are quantum spin liquid (QSL) states, in which no long-range magnetic ordering appears at low temperatures due to strong quantum fluctuations of the magnetic moments. The existing QSL candidates all have their intrinsic disadvantages, however, and solid evidence for quantum fluctuations is scarce. Here, we report a previously unreported compound, N a 2 B a C o ( P O 4 ) 2 , a geometrically frustrated system with effective spin-1/2 local moments for Co 2+ ions on an isotropic 2-dimensional (2D) triangular lattice. Magnetic susceptibility and neutron scattering experiments show no magnetic ordering down to 0.05 K. Thermodynamic measurements show that there is a tremendous amount of magnetic entropy present below 1 K in 0-applied magnetic field. The presence of localized low-energy spin fluctuations is revealed by inelastic neutron measurements. At low applied fields, these spin excitations are confined to low energy and contribute to the anomalously large specific heat. In larger applied fields, the system reverts to normal behavior as evident by both neutron and thermodynamic results. Our experimental characterization thus reveals that this material is an excellent candidate for the experimental realization of a QSL state.},
doi = {10.1073/pnas.1906483116},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
number = 29,
volume = 116,
place = {United States},
year = {2019},
month = {7}
}
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Journal Article:
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DOI: 10.1073/pnas.1906483116
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Works referenced in this record:

Crystal structure refinement with SHELXL
journal, January 2015

  • Sheldrick, George M.
  • Acta Crystallographica Section C Structural Chemistry, Vol. 71, Issue 1, p. 3-8
  • DOI: 10.1107/S2053229614024218

Single-crystal structure validation with the program PLATON
journal, January 2003

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