Theoretical spin-wave dispersions in the antiferromagnetic phase AF1 of MnWO$_4$ based on the polar atomistic model in P2

TL;DR

This paper provides a theoretical analysis of spin-wave dispersions in the antiferromagnetic phase of MnWO$_4$, revealing the influence of spin canting and confirming the material's hidden polar character through a detailed atomistic model.

Contribution

It introduces a polar atomistic model based on a Heisenberg framework to accurately describe spin-wave excitations in MnWO$_4$'s AF1 phase, including a newly observed low-energy mode.

Findings

Spin wave dispersions are highly sensitive to spin canting configurations.

The model successfully reproduces the low-lying excitation mode at 0.45 meV.

Results support the hidden polar character of MnWO$_4$.

Abstract

The spin wave dispersions of the low temperature antiferromagnetic phase (AF1) MnWO$_4$ have been numerically calculated based on the recently reported non-collinear spin configuration with two different canting angles. A Heisenberg model with competing magnetic exchange couplings and single-ion anisotropy terms could properly describe the spin wave excitations, including the newly observed low-lying energy excitation mode $\omega_2$=0.45 meV appearing at the magnetic zone centre. The spin wave dispersion and intensities are highly sensitive to two differently aligned spin-canting sublattices in the AF1 model. Thus this study reinsures the otherwise hardly provable hidden polar character in MnWO$_4$.