Out-of-plane polarization and topological magnetic vortices in multiferroic CrPSe$_3$

TL;DR

This study uses first-principles calculations to reveal out-of-plane polarization and topological magnetic vortices in 2D multiferroic CrPSe$_3$, highlighting its potential for electric field control of magnetic states.

Contribution

It uncovers intrinsic ferroelectric and antiferroelectric phases in CrPSe$_3$ with coupled magnetic and electric orders, a novel finding in 2D multiferroics.

Findings

CrPSe$_3$ exhibits ferroelectric and antiferroelectric phases with ferromagnetic order.

Out-of-plane electric field can switch the magnetic ground state.

Presence of topological magnetic vortices like meron pairs in these phases.

Abstract

Two-dimensional (2D) multiferroic materials are ideal systems for exploring new coupling mechanisms between different ferroic orders and producing novel quantum phenomena with potential applications. We employed first-principles density functional theory calculations to discover intrinsic ferroelectric and anti-ferroelectric phases of CrPSe$_3$, which show ferromagnetic order and compete with the centrosymmetric phase with an antiferromagnetic order. Our analysis show that the electrical dipoles of such type-I multiferroic phases come from the out-of-plane displacements of phosphorus ions due to the stereochemically active lone pairs. The coupling between polar and magnetic orders creates the opportunity for tunning the magnetic ground state by switching from the centrosymmetric to the ferroelectric phase using an out-of-plane electric field. In ferroelectric and antiferroelectric phases, the combination of easy-plane anisotropy and Dzyaloshinskii-Moriya interactions (DMI) indicate they can host topological magnetic vortices like meron pairs.