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, MnPSe3, 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, TN=74K, 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 J1ab=0.45 meV, J2ab=0.03 meV, J3ab=0.19 meV, consistent with theoretical predictions. Despite the quasi-2D behavior, appreciable interlayer interactions of Jc=0.031(5) meV are required to model the data. No evidence for anisotropy in the form of a spin gap is observed in the data collected. The measurements on MnPSe3 are contrasted with those on MnPS3 and reveal a large increase in the interlayer exchange interaction in MnPSe3 that may stabilize the similar ordering temperatures in the bulk compounds.
