TY - JOUR
T1 - Strong quantum fluctuations in a quantum spin liquid candidate with a Co-based triangular lattice
AU - Zhong, Ruidan
AU - Guo, Shu
AU - Xu, Guangyong
AU - Xu, Zhijun
AU - Cava, Robert J.
N1 - Funding Information:
ACKNOWLEDGMENTS. We acknowledge the Applications Group at Quantum Design for measuring the ac susceptibility between 0.05 and 0.35 K. We are thankful for the support of the National Institute of Standards and Technology, US Department of Commerce for providing the neutron research facilities used in this work. We thank N. P. Ong and J. Tranquada for helpful discussions and communications. The materials synthesis and magnetic characterization was supported by Gordon and Betty Moore Emergent Phenomena in Quantum System (EPiQS) Program Grant GBMF-4412. The crystal structure determination was supported by US Department of Energy, Office of Science, Emergent Frontier Research Centers (EFRC) Grant DE-SC0019331.
Funding Information:
We acknowledge the Applications Group at Quantum Design for measuring the ac susceptibility between 0.05 and 0.35 K. We are thankful for the support of the National Institute of Standards and Technology, US Department of Commerce for providing the neutron research facilities used in this work. We thank N. P. Ong and J. Tranquada for helpful discussions and communications. The materials synthesis and magnetic characterization was supported by Gordon and Betty Moore Emergent Phenomena in Quantum System (EPiQS) Program Grant GBMF-4412. The crystal structure determination was supported by US Department of Energy, Office of Science, Emergent Frontier Research Centers (EFRC) Grant DE-SC0019331.
Publisher Copyright:
© 2019 National Academy of Sciences. All rights reserved.
PY - 2019
Y1 - 2019
N2 - 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, Na2BaCo(PO4)2, a geometrically frustrated system with effective spin-1/2 local moments for Co2 + 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.
AB - 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, Na2BaCo(PO4)2, a geometrically frustrated system with effective spin-1/2 local moments for Co2 + 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.
KW - Fluctuations
KW - Geometric frustrated magnets
KW - Quantum
KW - Quantum spin liquids
KW - Triangular lattice
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U2 - 10.1073/pnas.1906483116
DO - 10.1073/pnas.1906483116
M3 - Article
C2 - 31266895
AN - SCOPUS:85069054591
SN - 0027-8424
VL - 116
SP - 14505
EP - 14510
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 29
ER -