Semiclassical spin liquid state of easy axis Kagome antiferromagnets

TL;DR

This paper explores how strong easy axis anisotropy in Kagome antiferromagnets leads to a semiclassical spin liquid state at low temperatures, distinct from classical Ising behavior, due to quantum effects.

Contribution

It demonstrates that quantum transverse dynamics induce a crossover from classical to semiclassical spin liquid behavior in easy axis Kagome antiferromagnets.

Findings

Identification of a temperature crossover driven by quantum interactions.

Distinct short-range correlations characterize the spin liquid state.

Quantum effects modify classical Ising models at low temperatures.

Abstract

Motivated by recent experiments on Nd-langasite, we consider the effect of strong easy axis single-ion anisotropy $D$ on $S > 3/2$ spins interacting with antiferromagnetic exchange $J$ on the Kagome lattice. When $T \ll DS^2$, the collinear low energy states selected by the anisotropy map on to configurations of the classical Kagome lattice Ising antiferromagnet. However, the low temperature limit is quite different from the cooperative Ising paramagnet that obtains classically for $T \ll JS^2$. We find that sub-leading ${\mathcal O}(J^3S/D^2)$ multi-spin interactions arising from the transverse quantum dynamics result in a crossover from an intermediate temperature classical cooperative Ising paramagnet to a semiclassical spin liquid with distinct short-ranged correlations for $T \ll J^3S/D^2$.