Spin stiffness and quantum fluctuations in C-type and A-type antiferromagnets

TL;DR

This study uses linear spin-wave theory to analyze quantum fluctuations in C-type and A-type antiferromagnets, revealing small quantum effects in certain materials and their limitations in explaining experimental observations.

Contribution

It provides a systematic analysis of quantum fluctuations in specific antiferromagnetic phases using spin-wave theory, highlighting the limited quantum effects in certain cubic materials.

Findings

Quantum corrections decrease with more ferromagnetic bonds.

Quantum effects are small in LaMnO_3 and LaVO_3.

Cannot account for the observed reduction in magnetic order parameter.

Abstract

We present a systematic study of quantum fluctuations in the C-type and A-type antiferromagnetic (AF) phases in cubic lattices and in bilayer systems. Using the linear spin-wave theory, we show that the spin stiffness and the quantum corrections to the order parameter and energy obtained for C-AF and A-AF phases decrease with the increasing number of ferromagnetic bonds. Therefore, the quantum spin effects in LaMnO_3 and in LaVO_3 are rather small, suggesting the magnetic moments of 3.91 and 1.89 Bohr's magneton, respectively. They cannot explain the strong reduction of the magnetic order parameter observed in cubic vanadates.