Antiferromagnetism in the magnetoelectric effect single crystal LiMnPO$_4$

TL;DR

This study investigates the antiferromagnetic properties and spin dynamics of LiMnPO$_4$, revealing detailed magnetic transition behavior and spin-wave characteristics through neutron scattering, contributing to understanding magnetoelectric coupling.

Contribution

The paper provides detailed neutron scattering analysis of LiMnPO$_4$, modeling its spin-wave dispersion with a comprehensive Hamiltonian, and links spin dynamics to magnetic order.

Findings

LiMnPO$_4$ is antiferromagnetic below 33.75 K.

Spin-wave dispersion is well modeled by a linear spin-wave framework.

Temperature-dependent spin dynamics relate to magnetic order parameter.

Abstract

Elastic and inelastic neutron scattering studies reveal details of the antiferromagnetic tansition and intriguing spin-dynamics in the magneto-electric effect single crystal LiMnPO$_4$. The elastic scattering studies confirm the system is antiferromagnetic (AFM) below $T_N$=33.75 K with local magnetic moments (Mn$^{2+}$; $S = 5/2$) that are aligned along the crystallographic a-axis. The spin-wave dispersion curves propagating along the three principal axes, determined by inelastic scattering, are adequately modeled in the linear spin-wave framework assuming a spin-Hamiltonian that is parameterized by inter- and in-plane nearest- and next-nearest-neighbor interactions, and by easy-plane anisotropy. The temperature dependence of the spin dynamics makes this an excellent model many-body spin system to address the question of the relationship between spin-wave excitations and the order parameter.