A Schwinger-boson approach to the kagome with Dzyaloshinskii-Moriya interactions: phase diagram and dynamical structure factors

TL;DR

This paper uses Schwinger-boson mean-field theory to map the phase diagram of the kagome antiferromagnet with Dzyaloshinskii-Moriya interactions, revealing quantum phase transitions and calculating structure factors relevant for experiments.

Contribution

It provides the first zero-temperature phase diagram including topological spin liquids and Neel phases for this model, with calculations of structure factors for experimental comparison.

Findings

Identified quantum phase transitions between spin liquids and Neel phases.

Calculated equal-time and dynamical structure factors for different phases.

Found qualitative agreement with exact diagonalization in certain regimes.

Abstract

We have obtained the zero-temperature phase diagram of the kagome antiferromagnet with Dzyaloshinskii-Moriya interactions in Schwinger-boson mean-field theory. We find quantum phase transitions (first or second order) between different topological spin liquids and Neel ordered phases (either the $\sqrt{3} \times \sqrt{3}$ state or the so-called Q=0 state). In the regime of small Schwinger-boson density, the results bear some resemblances with exact diagonalization results and we briefly discuss some issues of the mean-field treatment. We calculate the equal-time structure factor (and its angular average to allow for a direct comparison with experiments on powder samples), which extends earlier work on the classical kagome to the quantum regime. We also discuss the dynamical structure factors of the topological spin liquid and the Neel ordered phase.