Abstract
A quantum spin liquid (QSL) is an exotic state of matter in which electrons' spins are quantum entangled over long distances, but do not show magnetic order in the zero-temperature limit. The observation of QSL states is a central aim of experimental physics, because they host collective excitations that transcend our knowledge of quantum matter; however, examples in real materials are scarce. Here, we report neutron-scattering experiments on YbMgGaO 4 , a QSL candidate in which Yb 3+ ions with effective spin-1/2 occupy a triangular lattice. Our measurements reveal a continuum of magnetic excitations-the essential experimental hallmark of a QSL-at very low temperature (0.06 K). The origin of this peculiar excitation spectrum is a crucial question, because isotropic nearest-neighbour interactions do not yield a QSL ground state on the triangular lattice. Using measurements in the field-polarized state, we identify antiferromagnetic next-nearest-neighbour interactions, spin-space anisotropies, and chemical disorder between the magnetic layers as key ingredients in YbMgGaO 4 .
| Original language | English |
|---|---|
| Pages (from-to) | 117-122 |
| Number of pages | 6 |
| Journal | Nature Physics |
| Volume | 13 |
| Issue number | 2 |
| DOIs | |
| State | Published - Feb 1 2017 |
Funding
We are very grateful to L. Ge for his help with heat-capacitymeasurements and J. Carruth, S. Elorfi, M. Everett and C. Fletcher for sample environment and instrument support during our neutron-scattering experiments. It is our pleasure to thank S. Chernyshev, R. Coldea, K. Ross, M. Waterbury, Y. Wan and M. Zhitomirsky for insightful discussions. The work and equipment at the Georgia Institute of Technology (J.A.M.P., M.D. and M.M.) was supported by the College of Sciences and the Executive Vice-President for Research. The work at the University of Tennessee (Z.D. and H.Z.) was supported by the National Science Foundation through award DMR-1350002. The research at Oak Ridge National Laboratory's Spallation Neutron Source was sponsored by the US Department of Energy, Office of Basic Energy Sciences, Scientific User Facilities Division. We are very grateful to L. Ge for his help with heat-capacity measurements and J. Carruth, S. Elorfi, M. Everett and C. Fletcher for sample environment and instrument support during our neutron-scattering experiments. It is our pleasure to thank S. Chernyshev, R. Coldea, K. Ross, M. Waterbury, Y. Wan and M. Zhitomirsky for insightful discussions. The work and equipment at the Georgia Institute of Technology (J.A.M.P., M.D. and M.M.) was supported by the College of Sciences and the Executive Vice-President for Research. The work at the University of Tennessee (Z.D. and H.Z.) was supported by the National Science Foundation through award DMR-1350002. The research at Oak Ridge National Laboratory\u2019s Spallation Neutron Source was sponsored by the US Department of Energy, Office of Basic Energy Sciences, Scientific User Facilities Division.