Emerging kinetic-exchange for the enhanced metallic ferromagnetism in CrGeTe$_3$ under pressure

TL;DR

This study explains how pressure induces a transition from semiconducting to metallic ferromagnetism in CrGeTe$_3$, highlighting the roles of electronic correlation and $d$-$p$ hybridization in this process.

Contribution

It introduces a unified theoretical framework explaining pressure-induced magnetic phase changes in CrGeTe$_3$ through reduced correlation and enhanced hybridization.

Findings

Pressure induces a transition from semiconducting to metallic ferromagnetism.

Enhanced $d$-$p$ hybridization correlates with increased Curie temperature.

Intraband excitations dominate the pressure effects on magnetic properties.

Abstract

The microscopic origin of ferromagnetism in correlated materials remains heavily debated, particularly for the competing mechanisms governing insulating versus metallic phases. In this work, we theoretically study the electronic structure evolution of CrGeTe$_{3}$ under pressure and provide a consistent explanation to three unique features of this system, i.e. the semiconducting ferromagnetism at low pressure, the metallic ferromagnetism at high pressure, and the enhanced Curie temperature in the metallic phase. We propose that it is the reduced electronic correlation and enhanced $d$-$p$ hybridization that universally drive the continuous evolution of CrGeTe$_{3}$ under pressure and glue the three distinct experimental observations. Central to our discovery is the dual role of metallicity -- it simultaneously establishes kinetically driven exchange via $d$-$p$ hybridization and enables Stoner-type magnetic instability, with the contribution also from the residual super-exchange. Our analyses reveal that {\it intraband} excitations dominate the pressure-enhanced $\omega_p^2$ and $T_c$ correlation. These findings establish $d$-$p$ hybridization and electronic correlation as the bridge between localized and itinerant magnetism, at least, in CrGeTe$_{3}$.