# Intrinsic magnetism in monolayer transition metal trihalides: a comparative study

## TL;DR

This study uses density functional theory to explore magnetic and electronic properties of monolayer transition metal tri-halides, revealing high-temperature ferromagnetism and spin-polarized Dirac half metallic states with potential spintronic applications.

## Contribution

It provides a comparative analysis of magnetic ordering and electronic states in monolayer transition metal tri-halides, identifying candidates with room-temperature ferromagnetism and spin-polarized Dirac half metals.

## Key findings

- Most tri-halides are ferromagnetic except FeX3 which is antiferromagnetic.
- VX3 and NiX3 have the highest magnetic transition temperatures, exceeding room temperature.
- Mn and Ni tri-halides are half metals or Dirac half metals, suitable for spintronics.

## Abstract

Two dimensional magnetic materials, with tunable electronic properties could lead to new spintronic, magnetic and magneto-optic applications. Here, we explore intrinsic magnetic ordering in two dimensional monolayers of transition metal tri-halides (MX$_3$, M = V, Cr, Mn, Fe and Ni, and X = F, Cl, Br and I), using density functional theory. We find that other than FeX$_3$ family which has an anti-ferromagnetic ground state, rest of the trihalides are ferromagnetic. Amongst these the VX$_3$ and NiX$_3$ family are found to have the highest magnetic transition temperature, beyond the room temperature. In terms of electronic properties, the tri-halides of Mn and Ni are either half metals or Dirac half metals, while the tri-halides of V, Fe and Cr are insulators. Among all the trihalides studied in this paper, we find the existence of very clean spin polarized Dirac half metallic state in MnF$_3$, MnCl$_3$, MnBr$_3$, NiF$_3$ and NiCl$_3$. These spin polarized Dirac half metals will be immensely useful for spin-current generation and other spintronic applications.