Many-body electronic structure, self-doped double-exchange, and Hund metallicity in 1T-CrTe2 bulk and monolayer

TL;DR

This paper uses advanced theoretical methods to reveal that 1T-CrTe2 is a Hund metal with a dual electronic nature, where electron correlations and magnetism interplay to produce high-temperature ferromagnetism, especially in bulk form.

Contribution

First detailed analysis showing 1T-CrTe2 as a self-doped double-exchange ferromagnet with Hund metallicity using DFT+DMFT.

Findings

Identified dual electronic nature of Cr-d orbitals in 1T-CrTe2.

Demonstrated Hund coupling mediates double-exchange ferromagnetism.

Structural deformation reduces Tc in monolayer 1T-CrTe2.

Abstract

The van der Waals (vdW) ferromagnet 1T-CrTe2 is an emerging spintronics platform, notable for its high Curie temperature (Tc) and intriguing transport properties. However, the fundamental interplay between the electron correlations and magnetism underlying its high Tc still remains elusive. Here, using density functional theory plus dynamical mean-field theory (DFT+DMFT), we identify 1T-CrTe2 as a self-doped double-exchange ferromagnet with pronounced Hund metallicity. This identification is grounded in the first detailed analysis of its many-body electronic structure, which reveals a dual electronic nature of Cr-d orbitals where itinerant eg electrons coexist with localized t2g moments. The interaction between these orbitals, mediated by Hund's coupling, drives the double-exchange ferromagnetism, establishing 1T-CrTe2 as a Hund metal reminiscent of orbital-selective Mott systems. In the monolayer limit, while this physical picture persists, structural deformation, rather than reduced dimensionality, notably reduces Tc.Our findings offer a new perspective on the high-Tc ferromagnetism in 1T-CrTe2, a mechanism potentially pivotal for other correlated two-dimensional vdW metallic magnets.