Magnetic exchange interactions in the van der Waals layered antiferromagnet MnPSe3

TL;DR

This study investigates magnetic exchange interactions in the 2D van der Waals antiferromagnet MnPSe3 using neutron scattering, revealing dominant intralayer and notable interlayer interactions, with persistent magnetic excitations above the ordering temperature.

Contribution

The paper provides a detailed model of the spin Hamiltonian for MnPSe3, highlighting the significant interlayer interactions and comparing them with related compounds.

Findings

Magnetic excitations persist above T_N, indicating low-dimensional magnetic behavior.

Intralayer exchange interactions are quantified with specific coupling constants.

Interlayer interactions are larger in MnPSe3 compared to MnPS3, despite similar 2D magnetic characteristics.

Abstract

Two-dimensional van der Waals compounds with magnetic ions on a honeycomb lattice are hosts to a variety of exotic behavior. The magnetic interactions in one such compound, MnPSe$_3$, are investigated with elastic and inelastic neutron scattering. Magnetic excitations are observed in the magnetically ordered regime and persist to temperatures well above the ordering temperature, $\rm T_N$ = 74 K, consistent with low dimensional magnetic interactions. The inelastic neutron scattering results allow a model spin Hamiltonian to be presented that includes dominant intralayer interactions of $J_{1ab}$=0.45 meV, $J_{2ab}$=0.03 meV, $J_{3ab}$=0.19 meV, and appreciable interlayer interactions of $J_c$=0.031(5) meV. No evidence for anisotropy in the form of a spin-gap is observed in the data collected. The measurements on MnPSe$_3$ are contrasted with those on MnPS$_3$ and reveal a large increase in the interlayer exchange interactions in MnPSe$_3$, despite the quasi-2D magnetic behavior.