Spin liquid phase due to competing classical orders in the semiclassical theory of the Heisenberg model with ring exchange on an anisotropic triangular lattice

TL;DR

This paper uses linear spin wave theory to show that ring exchange interactions induce a quantum disordered spin liquid phase in the anisotropic triangular Heisenberg model, especially in the frustration zone where classical orders compete.

Contribution

It demonstrates that quantum disordered regions arise from competing classical orders due to ring exchange, identifying the 'Goldilocks zone' for spin liquids in this model.

Findings

Ring exchange induces a quantum disordered region.

Spin liquid appears in the 'Goldilocks zone' of frustration.

Correspondence with experimental spin liquids in organic salts.

Abstract

Linear spin wave theory shows that ring exchange induces a quantum disordered region in the phase diagram of the title model. Spin wave spectra show that this is a direct manifestation of competing classical orders. A spin liquid is found in the `Goldilocks zone' of frustration, where the quantum fluctuations are large enough to cause strong competition between different classical orderings but not strong enough to stabilize spiral order. We note that the spin liquid phases of $\kappa$-(BEDT-TTF)${_2}X$ and $Y$[Pd(dmit)$_2$]$_2$ are found in this Goldilocks zone.