# Multiple Dirac Cones and Topological Magnetism in Honeycomb-Monolayer Transition Metal Trichalcogenides

## TL;DR

This paper predicts that monolayer transition metal trichalcogenides with honeycomb structures can host multiple Dirac cones, exhibit tunable gaps, and become topological ferromagnets with high Chern numbers due to electron correlations and doping.

## Contribution

It introduces a new class of 2D materials with multiple Dirac cones and topological magnetism, expanding the understanding of correlated Dirac electrons in honeycomb monolayers.

## Key findings

- Multiple Dirac cones with tunable gaps identified.
- Transition to topological ferromagnet with high Chern number.
- Potential for new atomically thin heterostructures.

## Abstract

The discovery of monolayer graphene has initiated two fertile fields in modern condensed matter physics, Dirac semimetals and atomically-thin layered materials. When these trends meet again in transition metal compounds, which possess spin and orbital degrees of freedom and strong electron correlations, more exotic phenomena are expected to emerge in the cross section of topological states of matter and Mott physics. Here, we show by using ab initio calculations that a monolayer form of transition metal trichalcogenides (TMTs), which has a honeycomb network of transition metal cations, may exhibit multiple Dirac cones with tunable gaps in the electronic structure. Furthermore, we elucidate that electron correlations and carrier doping turn the multiple-Dirac semimetal into a topological ferromagnet with high Chern number. Our findings raise the honeycomb-monolayer TMTs to a new paradigm to explore correlated Dirac electrons and topologically-nontrivial magnetism. In turn, the unique wide-ranging properties of the materials will deliver new building blocks for atomically thin heterostructures.