Spin Dynamics of the Triangular Heisenberg Antiferromagnet: A Schwinger Boson Approach

TL;DR

This paper uses a Schwinger boson mean-field approach to study the spin dynamics of the triangular Heisenberg antiferromagnet, revealing finite-spin effects on excitation modes not captured by linear spin wave theory.

Contribution

It introduces a Schwinger boson framework to analyze finite-spin effects in the triangular antiferromagnet, extending beyond linear spin wave theory results.

Findings

Modes at ordering wave vectors acquire a mass for finite spin

Results agree with LSWT in the infinite spin limit

Finite-spin effects lead to gapped excitations

Abstract

We have analyzed the two-dimensional antiferromagnetic Heisenberg model on the triangular lattice using a Schwinger boson mean-field theory. By expanding around a state with local $120^\circ$ order, we obtain, in the limit of infinite spin, results for the excitation spectrum in complete agreement with linear spin wave theory (LSWT). In contrast to LSWT, however, the modes at the ordering wave vectors acquire a mass for finite spin. We discuss the origin of this effect.