Prediction of High Curie Temperature, Large Magnetic Crystal Anisotropy in 2D Ferromagnetic Co$_2$Ge$_2$Te$_6$ Monolayer and Multilayer

TL;DR

This paper predicts that Co$_2$Ge$_2$Te$_6$ monolayer and multilayer structures exhibit high Curie temperatures, large magnetic anisotropy, and stable ferromagnetic half-metallicity, making them promising for spintronic applications.

Contribution

It introduces the first detailed theoretical prediction of high-temperature ferromagnetism and large magnetic anisotropy in 2D Co$_2$Ge$_2$Te$_6$ monolayers and multilayers, including stability and stacking effects.

Findings

Co$_2$Ge$_2$Te$_6$ monolayer has a Curie temperature of 161 K.

Monolayer exhibits in-plane magnetic anisotropy with MAE of -10.2 meV/f.u.

Multilayers maintain ferromagnetic half-metallicity regardless of stacking order.

Abstract

The Co$_2$Ge$_2$Te$_6$ shows intrinsic ferromagnetic (FM) order, which origins from superexchange interaction between Co and Te atoms, with higher Curie temperature ($T_c$) of 161 K. Co$_2$Ge$_2$Te$_6$ monolayer (ML) is half-metal (HM), and spin-$\beta$ electron is a semiconductor with gap of 1.311 eV. Co$_2$Ge$_2$Te$_6$ ML tends in-plane anisotropy (IPA), with magnetic anisotropy energy (MAE) of -10.2 meV/f.u.. Co$_2$Ge$_2$Te$_6$ ML shows good dynamical and thermal stability. Most interestingly, bilayers present ferromagnetic half-metallicity independent of the stacking orders. Notley, the multilayers ($N\ge 6$) present ferromagnetic HM, while the magnetoelectronic properties are related with the stacking patterns in thinner multilayers. Moreover, the magnetoelectronic properties are dependent on the stacking orders of bulk. The magnetic order with multilayers is determined by the super-super exchange and weak van der Waals (vdW) interaction. Co$_2$Ge$_2$Te$_6$ with intrinsic ferromagnetism, good stability of ferromagnetism and half-metallicity could help researchers to investigate its wide application in the spintronics.