Abstract
The emergence of a quantum spin liquid (QSL), a state of matter that can result when electron spins are highly correlated but do not become ordered, has been the subject of a considerable body of research in condensed matter physics [1,2]. Spin liquid states have been proposed as hosts for high-temperature superconductivity [3] and can host topological properties with potential applications in quantum information science [4]. The excitations of most quantum spin liquids are not conventional spin waves but rather quasiparticles known as spinons, whose existence is well established experimentally only in one-dimensional systems; the unambiguous experimental realization of QSL behavior in higher dimensions remains challenging. Here, we investigate the novel compound YbZn2GaO5, which hosts an ideal triangular lattice of effective spin-1/2 moments with no detectable inherent chemical disorder. Thermodynamic and inelastic neutron scattering measurements performed on high-quality single crystal samples of YbZn2GaO5 exclude the possibility of long-range magnetic ordering down to 0.06 K, demonstrate a quadratic power law for the specific heat and reveal a continuum of magnetic excitations in parts of the Brillouin zone. Both low-temperature thermodynamics and inelastic neutron scattering spectra suggest that YbZn2GaO5 is a U(1) Dirac QSL with spinon excitations concentrated at certain points in the Brillouin zone. We advanced these results by performing additional specific heat measurements under finite fields, further confirming the theoretical expectations for a Dirac QSL on the triangular lattice of YbZn2GaO5.
| Original language | English |
|---|---|
| Article number | 266703 |
| Journal | Physical Review Letters |
| Volume | 133 |
| Issue number | 26 |
| DOIs | |
| State | Published - Dec 31 2024 |
Funding
We would like to express our gratitude to Patrick A. Lee, Cristian D. Batista, and Sachith E. Dissanayake for their valuable contributions to our discussions. We are thankful to Chun-Hsing Chen and the X-Ray Core Laboratory of the Department of Chemistry at the University of North Carolina at Chapel Hill for their help with single-crystal x-ray diffraction measurements. Work performed at Duke University is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award No. DE-SC0023405. Work performed at the University of California, Berkeley, is supported by the U.S. Department of Energy, Office of Science, National Quantum Information Science Research Centers, Quantum Science Center. N.\u2009S. is additionally supported by the Theory Institute for Materials and Energy Spectroscopies (TIMES) of the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-05CH11231. R.\u2009B. acknowledges the support provided by Fritz London Endowed Postdoctoral Research Fellowship. This research used resources of the Spallation Neutron Source at Oak Ridge National Laboratory, which is a DOE Office of Science User Facility. A portion of this work was performed at the National High Magnetic Field Laboratory, which is supported by National Science Foundation Cooperative Agreement No. DMR-2128556 and the State of Florida.