Van der Waals Stacked 2D-Layered Co2Ge2Te6 with High Curie Temperature and Large Magnetic Crystal Anisotropy

Abstract

Co₂Ge₂Te₆ shows an intrinsic ferromagnetic order, which originates from the superexchange interaction between Co and Te atoms, with a Curie temperature of 161 K. The Co₂Ge₂Te₆ monolayer is half-metal, and the spin-β electron is a semiconductor with a gap of 1.311 eV. The Co₂Ge₂Te₆ monolayer shows in-plane anisotropy, with a magnetic anisotropy energy (MAE) of −10.2 meV/f.u., and Te atoms contribute −9.94 meV/f.u. Moreover, the bilayer with AA- and AB-stackings has MAEs of −24.659 and −24.492 meV/.f.u., respectively. Most interestingly, bilayers present ferromagnetic half-metallicity independent of stacking orders. The multilayers (N ≥ 6) present ferromagnetic half metal, while magnetoelectronic properties are related with stacking patterns in thinner multilayers. Moreover, the magnetoelectronic properties of bulk are related with stacking patterns. The multilayers’ magnetic orders are determined by the super–super exchange and weak van der Waals (vdW) interaction. Moreover, the Co₂Ge₂Te₆ monolayer and multilayers show good dynamical and thermal stability. These findings could pave the way of application of intrinsic ferromagnetic Co₂Ge₂Te₆ in the spintronics.