Spin-Wave Theory of the Multiple-Spin Exchange Model on a Triangular Lattice in a Magnetic Field : 3-Sublattice Structures

TL;DR

This paper investigates the spin wave behavior in a triangular lattice multiple-spin exchange model under a magnetic field, revealing the stability of certain ground states and phase transitions through linear spin-wave theory.

Contribution

It provides a detailed analysis of the stability of coplanar three-sublattice states and identifies phase transitions involving 6-sublattice structures in the model.

Findings

Y-shape ground state persists under quantum fluctuations

Phase transition to 6-sublattice structure with spin wave softening

Quantum corrections to sublattice magnetizations estimated

Abstract

We study the spin wave in the S=1/2 multiple-spin exchange model on a triangular lattice in a magnetic field within the linear spin-wave theory. We take only two-, three- and four-spin exchange interactions into account and restrict ourselves to the region where a coplanar three-sublattice state is the mean-field ground state. We found that the Y-shape ground state survives quantum fluctuations and the phase transition to a phase with a 6-sublattice structure occurs with softening of the spin wave. We estimated the quantum corrections to the ground state sublattice magnetizations due to zero-point spin-wave fluctuations.