Influence of Dzyaloshinskii-Moriya interactions on magnetic structure of a spin-1/2 deformed kagome lattice antiferromagnet

TL;DR

This study explores how Dzyaloshinskii-Moriya interactions influence the magnetic structure and excitations in a spin-1/2 deformed kagome lattice antiferromagnet, aligning theoretical models with experimental observations.

Contribution

The paper develops a bond operator mean-field theory incorporating Dzyaloshinskii-Moriya interactions to explain experimental magnetic phenomena in Rb2Cu3SnF12.

Findings

Dzyaloshinskii-Moriya interactions significantly alter triplon dispersions.

The spin gap shifts from K to Gamma point due to these interactions.

Results align with neutron scattering and magnetization experiments.

Abstract

Motivated by the recent neutron scattering experiment on Rb2Cu3SnF12 [Nat. Phys. 6, 865 (2010)], we investigate the effect of Dzyaloshinskii-Moriya interactions in a theoretical model for the magnetic structure of this material. Considering the valence bond solid ground state, which has a 12-site unit cell, we develop the bond operator mean-field theory. It is shown that the Dzyaloshinskii-Moriya interactions significantly modify the triplon dispersions around the Gamma point and cause a shift of the spin gap (the minimum triplon gap) position from the K to Gamma point in the first Brilloin zone. The spin gap is also evaluated in exact diagonalization studies on a 24-site cluster. We discuss a magnetic transition induced by the Dzyaloshinskii-Moriya interactions in the bond operator framework. Moreover, the magnetization process under external magnetic fields is studied within the exact diagonalization and strong coupling expansion approaches. We find that the results of all above approaches are consistent with the experimental findings.