Magnetic Anisotropy and Magnetic Ordering of Transition-Metal Phosphorus Trisulfides

Abstract

A magnetic model with an unprecedentedly large number of parameters was determined from first-principles calculations for transition-metal phosphorus trisulfides (TMPS3's), reproducing the measured magnetic ground states of bulk TMPS3's. Our Monte Carlo simulations for the critical temperature, magnetic susceptibility, and specific heat of bulk and few-layer TMPS3's agree well with available experimental data and show that the antiferromagnetic order of TMPS3's persists down to monolayers. Remarkably, the orbital polarization, neglected in recent first-principles studies, dramatically enhances the magnetic anisotropy of FePS3 by almost 2 orders of magnitude. A recent Raman study [Kim, K., et al. Nat. Commun. 2019, 10, 345] claimed that magnetic ordering is absent in monolayer NiPS3 but simultaneously reported a strong two-magnon continuum; we show that the criterion used to judge magnetic ordering therein is invalid for monolayer NiPS3, providing an understanding of the two seemingly contradictory experimental results. The rich predictions on the magnetic susceptibility and specific heat of few-layer TMPS3's await experimental verifications.