Magnetic exchange interactions in the van der Waals layered antiferromagnet MnPSe3

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, ${\mathrm{T}}_{\mathrm{N}}$ = 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.