2D-XY ferromagnetism with high transition temperature in Janus monolayer V$_{2}$XN (X = P, As)

TL;DR

This study predicts Janus monolayer V$_{2}$XN as high-temperature 2D-XY ferromagnets with potential for spintronic devices, supported by first-principles calculations and Monte Carlo simulations showing BKT transition above room temperature.

Contribution

First-principles prediction of high-temperature 2D-XY ferromagnetism in Janus monolayer V$_{2}$XN with detailed analysis of magnetic properties and strain effects.

Findings

V$_{2}$AsN has a MAE of 292 μeV per V atom.

T_BKT exceeds 434 K in V$_{2}$AsN.

Strain of 5% raises T_BKT above 500 K.

Abstract

Two-dimensional (2D) XY magnets with easy magnetization planes support the nontrivial topological spin textures whose dissipationless transport is highly desirable for 2D spintronic devices. Here, we predicted that Janus monolayer V$_{2}$XN (X = P, As) with a square lattice are 2D-XY ferromagnets by first-principles calculations. Both the magnetocrystalline anisotropy and magnetic shape anisotropy favor an in-plane magnetization, leading to an easy magnetization $xy$-plane in Janus monolayer V$_{2}$XN. Resting on the Monte Carlo simulations, we observed the Berezinskii-Kosterlitz-Thouless (BKT) phase transition in monolayer V$_{2}$XN with transition temperature $T_{\rm BKT}$ being above the room temperature. Especially, monolayer V$_{2}$AsN has a magnetic anisotropy energy (MAE) of 292.0 $\mu$eV per V atom and a $T_{\rm BKT}$ of 434 K, which is larger than that of monolayer V$_{2}$PN. Moreover, a tensile strain of 5\% can further improve the $T_{\rm BKT}$ of monolayer V$_{2}$XN to be above 500 K. Our results indicated that Janus monolayer V$_{2}$XN (X = P, As) were candidate materials to realize high-temperature 2D-XY ferromagnetism for spintronics applications.