VI3: a 2D Ising ferromagnet

TL;DR

This paper proposes VI3 as a promising 2D Ising ferromagnet with tunable Curie temperature, based on computational analyses, highlighting its potential for spintronic applications.

Contribution

The study introduces VI3 as a novel 2D Ising ferromagnet and demonstrates how tensile strain enhances its magnetic properties through detailed theoretical calculations.

Findings

VI3 exhibits 2D Ising ferromagnetism due to specific electronic states.

Tensile strain increases the Curie temperature from 70 K to 90-110 K.

Identification of spin-orbital states with strong single ion anisotropy.

Abstract

Two-dimensional (2D) magnetic materials are of great current interest for their promising applications in spintronics. Here we propose the van der Waals (vdW) material VI3 to be a 2D Ising ferromagnet (FM), using density functional calculations, crystal field level diagrams, superexchange model analyses, and Monte Carlo simulations. The $a_{1g}$$^1$$e'_{-}$$^1$ ground state in the trigonal crystal field gives rise to the 2D Ising FM due to a significant single ion anisotropy (SIA) and enhanced FM superexchange both associated with the $S_z$=1 and $L_z$=--1 state of V3+ ions. We find that a tensile strain on the VI3 monolayer further stabilizes the $a_{1g}$$^1$$e'_{-}$$^1$ ground state, and its Curie temperature ($T_{\rm C}$) would increase from 70 K to 90-110 K under a 2.5-5\% tensile strain. Moreover, we suggest a group of spin-orbital states with a strong SIA which may help to search more 2D Ising magnets.