Spin Disorder on a Triangular Lattice

TLDR

In magnets, cooling typically induces periodic spin order, but theory predicted that triangular lattice spins could form a liquid‑like disordered state at low temperatures, a possibility that has remained an active question. Neutron and thermodynamic studies of NiGa₂S₄ show that geometrical frustration stabilizes a low‑temperature spin‑disordered state with coherence beyond two‑spin correlations, suggesting spin‑liquid behavior.

Abstract

As liquids crystallize into solids on cooling, spins in magnets generally form periodic order. However, three decades ago, it was theoretically proposed that spins on a triangular lattice form a liquidlike disordered state at low temperatures. Whether or not a spin liquid is stabilized by geometrical frustration has remained an active point of inquiry ever since. Our thermodynamic and neutron measurements on NiGa 2 S 4 , a rare example of a two-dimensional triangular lattice antiferromagnet, demonstrate that geometrical frustration stabilizes a low-temperature spin-disordered state with coherence beyond the two-spin correlation length. Spin liquid formation may be an origin of such behavior.