First-principles study of electronic and magnetic properties of self-intercalated van der Waals magnet Cr$_3$Ge$_2$Te$_6$

TL;DR

This study uses first-principles calculations and simulations to explore the electronic and magnetic properties of the self-intercalated van der Waals magnet Cr$_3$Ge$_2$Te$_6$, revealing high Curie temperature, near half-metallicity, and potential for nano-electronic applications.

Contribution

It provides the first detailed theoretical analysis of Cr$_3$Ge$_2$Te$_6$, highlighting its high Curie temperature, large anomalous Hall effect, and robustness in thin-film form, advancing understanding of self-intercalated vdW magnets.

Findings

Cr$_3$Ge$_2$Te$_6$ has a Curie temperature of 492 K.

It exhibits nearly half-metallic behavior with up to 90.9% spin polarization.

Doping enhances anomalous Hall conductivity up to 648 Ω^{-1}cm^{-1}.

Abstract

Self-intercalated van der Waals magnets, characterized by self-intercalating native atoms into van der Waals layered structures with intrinsic magnetism, exhibit a variety of novel physical properties. Here, using first-principles calculations and Monte Carlo simulations, we report a self-intercalated van der Waals ferromagnet, Cr$_3$Ge$_2$Te$_6$, which has a high Curie temperature of 492 K. We find that Cr$_3$Ge$_2$Te$_6$ is nearly half-metallic with a spin polarization reaching up to 90.9%. Due to the ferromagnetism and strong spin-orbit coupling effect in Cr$_3$Ge$_2$Te$_6$, a large anomalous Hall conductivity of 138 $\Omega^{-1}$ cm$^{-1}$ and 305 $\Omega^{-1}$ cm$^{-1}$ can be realized when its magnetization is along its magnetic easy axis and hard axis, respectively. By doping electrons (holes) into Cr$_3$Ge$_2$Te$_6$, these anomalous Hall conductivities can be increased up to 318 $\Omega^{-1}$ cm$^{-1}$ (648 $\Omega^{-1}$ cm$^{-1}$). Interestingly, a 5-layer Cr$_3$Ge$_2$Te$_6$ thin film retains the room-temperature ferromagnetism with a higher spin polarization and larger anomalous Hall conductivity. Our work demonstrates that Cr$_3$Ge$_2$Te$_6$ is a novel room-temperature self-intercalated ferromagnet with high spin polarization and large anomalous Hall conductivity, offering great opportunities for designing nano-scale electronic devices.