Numerical study of fractionalization in an Easy-axis Kagome antiferromagnet

TL;DR

This study uses exact numerical calculations to demonstrate a broad spin liquid phase with topological degeneracy and fractionalized excitations in an easy-axis Kagome antiferromagnet, including explicit vison gap calculations.

Contribution

It provides the first explicit calculation of vison excitation gaps and dispersion in this model, expanding understanding of its spin liquid phase and phase transitions.

Findings

Identification of a broad spin liquid phase with topological degeneracy

Explicit calculation of vison excitation gap and dispersion

Observation of a first order transition to magnetic order

Abstract

Based on exact numerical calculations, we show that the generalized Kagome spin model in the easy axis limit exhibits a spin liquid, topologically degenerate ground state over a broad range of phase space. We present an (to our knowledge the first) explicit calculation of the gap (and dispersion) of ``vison'' excitations, and exponentially decaying spin and vison 2-point correlators, hallmarks of deconfined, fractionalized and gapped spinons. The region of the spin liquid phase includes a point at which the model is equivalent to a Heisenberg model with purely two-spin interactions. Beyond this range, a negative ``potential'' term tunes a first order transition to a magnetic ordered state. The nature of the phase transition is also discussed in light of the low energy spectrum. These results greatly expand the results and range of a previous study of this model in the vicinity of an exactly soluble point.