# Origin of Multiferroism in VOX2 (X = Cl, Br, I) Monolayers

## TL;DR

This paper explores the origin of multiferroic properties in VOX2 monolayers using a microscopic model and Green’s function method.

## Contribution

A new microscopic model is proposed to explain the multiferroic behavior and spin-reorientation transitions in VOX2 monolayers.

## Key findings

- Antisymmetric magnetoelectric interactions may cause spin-reorientation transitions without altering magnetic moment ordering.
- Changing the sign of exchange magnetic interaction along the b-axis leads to ferromagnetic ordering.
- The proposed model aligns with Density Functional Theory calculations.

## Abstract

Based on the proposed microscopic model, we investigate the multiferroic characteristics of VOX2 (X = Cl, Br, I) monolayers using a Green’s function method. The dependence of the microscopic parameters of the ferroelectric system (pseudo-spin arrangement and flipping rate) on the magnitude and sign of the exchange magnetic interaction along the b-axis and the value of the Dzyaloshinskii–Moria vector have been investigated and qualitatively explained. The possibility of observing a spin-reorientation transition with a change in the character of spin ordering from antiferromagnetic to ferromagnetic is investigated. It is found that the antisymmetric magnetoelectric interaction may be responsible for the spin-reorientation transition without a change in the ordering of magnetic moments. Changing the sign of the exchange magnetic interaction along the b-axis leads to ferromagnetic ordering without observing a spin-reorientation transition. The dependence of isotropic and antisymmetric magnetic interactions on the microscopic parameters of the ferroelectric system is qualitatively explained. A mechanism for the occurrence of the spin-reorientation transition is presented based on the proposed microscopic model. The obtained results qualitatively coincide with Density Functional Theory calculations.