Stable Ferromagnetism and High Curie Temperature in VGe$_2$N$_4$

TL;DR

This paper reports the discovery of a stable ferromagnetic VGe2Z4 monolayer with high Curie temperature and near-half-metallic properties, promising for spintronic applications.

Contribution

It identifies a new stable ferromagnetic monolayer in the MA2Z4 family with enhanced magnetic properties and strain-tunable Curie temperature, advancing low-dimensional magnetic materials.

Findings

VGe2Z4 monolayer is ferromagnetic and stable.

Magnetic ordering temperature can be increased by in-plane strain.

The material exhibits near-half-metallic electronic structure.

Abstract

The discovery of monolayer MA$_2$Z$_4$ (M = transition metals; A = IVA elements; Z = VA elements, Science 369, 2020, 670-674) family has led another advance for facilitating and harnessing magnetism in low-dimensional materials. However, only Cr and V based MA$_2$N$_4$ compounds exhibit intrinsic magnetism yet with unsatisfied magnetic ordering temperature. Herein, we identify a stable ferromagnetic number of this family, i.e., VGe$_2$Z$_4$ monolayer, by means of first-principles calculations. It is found that the magnetic configuration sustains under both compression and tensile uniaxial in-plane strain, and the former can act as a positive modulator to enhance magnetic ordering temperature (Tc). Electronic structure calculations reveal a large band gap in the spin down channel while band-gapless in the spin up channel, an impressive near-half-metallic character, which is a favorable candidate for spintronic device.