Quantum Fluctuation-Induced Phase Transition in S=1/2 XY-like Heisenberg Antiferromagnets on the Triangular Lattice

TL;DR

This paper investigates how quantum fluctuations influence the ground state selection in S=1/2 XY-like Heisenberg antiferromagnets on a triangular lattice under magnetic fields, revealing a dependence on anisotropy and field strength.

Contribution

It demonstrates the sensitivity of ground state selection to anisotropy and magnetic field, highlighting differences between classical and quantum models on different lattice geometries.

Findings

Ground state selection depends on anisotropy and magnetic field magnitude.

Classical and quantum models show similar state selection on the triangular lattice.

Differences in state selection are observed on the two-leg ladder lattice.

Abstract

The selection of the ground state among nearly degenerate states due to quantum fluctuations is studied for the S=1/2 XY-like Heisenberg antiferromagnets on the triangular lattice in the magnetic field applied along the hard axis, which was first pointed out by Nikuni and Shiba. We find that the selected ground state sensitively depends on the degree of the anisotropy and the magnitude of the magnetic field. This dependence is similar to that in the corresponding classical model at finite temperatures where various types of field induced phases appear due to the entropy effect. It is also found that the similarity of the selected states in the classical and quantum models are not the case in a two-leg ladder lattice, although the lattice consists of triangles locally and the ground state of this lattice in the classical case is the same as that of the triangular lattice.