# Ferromagnetic van der Waals crystal VI3

## TL;DR

This paper investigates the structural, magnetic, and electronic properties of the van der Waals crystal VI3, revealing its phase transition, ferromagnetism, insulating behavior, and potential as a 2D magnetic semiconductor platform.

## Contribution

It provides the first detailed analysis of VI3's structural transition, magnetic properties, and electronic structure, highlighting its potential for 2D magnetism research.

## Key findings

- VI3 undergoes a monoclinic to rhombohedral transition at ~79 K.
- VI3 exhibits ferromagnetic order below ~50 K.
- VI3 is a Mott insulator with a band gap of about 0.84 eV.

## Abstract

We report structural, physical properties and electronic structure of van der Waals (vdW) crystal VI3. Detailed analysis reveals that VI3 exhibits a structural transition from monoclinic C2/m to rhombohedral R-3 at Ts ~ 79 K, similar to CrX3 (X = Cl, Br, I). Below Ts, a long-range ferromagnetic (FM) transition emerges at Tc ~ 50 K. The local moment of V in VI3 is close to the high-spin state V3+ ion (S = 1). Theoretical calculation suggests that VI3 may be a Mott insulator with the band gap of about 0.84 eV. In addition, VI3 has a relative small interlayer binding energy and can be exfoliated easily down to few layers experimentally. Therefore, VI3 is a candidate of two-dimensional FM semiconductor. It also provides a novel platform to explore 2D magnetism and vdW heterostructures in S = 1 system.