Carrier and strain tunable intrinsic magnetism in two-dimensional MAX$_3$ transition metal chalcogenides

TL;DR

This study uses density functional theory to explore how carrier density and strain influence magnetic order in 2D MAX$_3$ transition metal chalcogenides, revealing tunable magnetic phases and potential for enhanced critical temperatures.

Contribution

It provides the first comprehensive ab initio analysis of carrier and strain effects on magnetism in a broad class of 2D MAX$_3$ compounds, identifying new ferromagnetic semiconductors and tunable magnetic states.

Findings

Most compounds are magnetic with diverse electronic properties.

Strain and gating can switch magnetic order between antiferromagnetic and ferromagnetic.

Carrier doping and strain significantly increase critical temperatures.

Abstract

We present a density functional theory study of the carrier-density and strain dependence of magnetic order in two-dimensional (2D) MAX$_3$ (M= V, Cr, Mn, Fe, Co, Ni; A= Si, Ge, Sn, and X= S, Se, Te) transition metal trichalcogenides. Our {\em ab initio} calculations show that this class of compounds includes wide and narrow gap semiconductors and metals and half-metals, and that most of these compounds are magnetic. Although antiferromagnetic order is most common, ferromagnetism is predicted in MSiSe$_3$ for M= Mn, Ni, in MSiTe$_3$ for M= V, Ni, in MnGeSe$_3$, in MGeTe$_3$ for M=Cr, Mn, Ni, in FeSnS$_3$, and in MSnTe$_3$ for M= V, Mn, Fe. Among these compounds CrGeTe$_3$ and VSnTe$_3$ are ferromagnetic semiconductors. Our calculations suggest that the competition between antiferromagnetic and ferromagnetic order can be substantially altered by strain engineering, and in the semiconductor case also by gating. The associated critical temperatures can be substantially enhanced by means of carrier doping and strains.