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arXiv · 1607.02615

Evidence for a spinon Fermi surface in a triangular lattice quantum spin liquid candidate

Yao Shen·Yao-Dong Li·Hongliang Wo·Yuesheng Li·Shoudong Shen·Bingying Pan·Qisi Wang·H. C. Walker·P. Steffens·M. Boehm·Yiqing Hao·D. L. Quintero-Castro·L. W. Harriger·M. D. Frontzek·Lijie Hao·Siqin Meng·Qingming Zhang·Gang Chen·Jun Zhao
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Abstract

A quantum spin liquid is an exotic quantum state of matter in which spins are highly entangled and remain disordered down to zero temperature. Such a state of matter is potentially relevant to high-temperature superconductivity and quantum-information applications, and experimental identification of a quantum spin liquid state is of fundamental importance for our understanding of quantum matter. Theoretical studies have proposed various quantum-spin-liquid ground states, most of which are characterized by exotic spin excitations with fractional quantum numbers (termed `spinon'). Here, we report neutron scattering measurements that reveal broad spin excitations covering a wide region of the Brillouin zone in a triangular antiferromagnet YbMgGaO4. The observed diffusive spin excitation persists at the lowest measured energy and shows a clear upper excitation edge, which is consistent with the particle-hole excitation of a spinon Fermi surface. Our results therefore point to a QSL state with a spinon Fermi surface in YbMgGaO4 that has a perfect spin-1/2 triangular lattice as in the original proposal of quantum spin liquids.

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Yao Shen, Yao-Dong Li, Hongliang Wo, Yuesheng Li, Shoudong Shen, Bingying Pan, Qisi Wang, H. C. Walker, P. Steffens, M. Boehm, Yiqing Hao, D. L. Quintero-Castro, L. W. Harriger, M. D. Frontzek, Lijie Hao, Siqin Meng, Qingming Zhang, Gang Chen, Jun Zhao. 2016-07-09. Evidence for a spinon Fermi surface in a triangular lattice quantum spin liquid candidate. https://doi.org/10.1038/nature20614

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