Highly Mobile Gapless Excitations in a Two-Dimensional Candidate Quantum Spin Liquid

TLDR

In antiferromagnets, geometric frustration on lattices such as the triangular lattice prevents magnetic ordering even at low temperatures, leading to a predicted quantum spin liquid state. The authors measured the thermal conductivity of the candidate QSL EtMe₃Sb[Pd(dmit)₂]₂ to characterize its lowest‑lying excitations. They observed both ballistically propagating gapless excitations and excitations associated with a finite spin gap, deepening understanding of this exotic state and its relevance to other two‑dimensional quantum systems. The study is attributed to Yamashita et al.

Abstract

Quantum Spin Liquid In antiferromagnets, the lowest-energy state is reached when neighboring spins on the underlying lattice point in opposite directions. Because of geometric constraints on some lattices (such as the two-dimensional triangular lattice), this magnetic ordering cannot be achieved even at temperatures close to absolute zero, and these compounds are predicted to be in a quantum spin liquid state. Yamashita et al. (p. 1246 ) measured the thermal conductivity of a recently identified candidate quantum spin liquid, the organic compound EtMe 3 Sb[Pd(dmit) 2 ] 2 , and characterized its lowest-lying excitations. Two types of excitations were observed: ballistically propagating gapless excitations and excitations associated with a finite spin gap. These results contribute to our understanding of this unusual state of matter, which is potentially relevant to other two-dimensional quantum systems.