Half-metal calculations of CoZrGe half-Heusler compound by using generalized gradient approximation (GGA) and modified Becke-Johnson (mBJ) methods

Abstract

The structural and magnetic calculations of CoZrGe half-Heusler compound were investigated using generalized gradient approximation (GGA) and modified Becke-Johnson potential. First, the volume-energy curves were performed to determine which phase was more stable. According to that curve, the ferromagnetic (FM) phase was more energetically stable than non-magnetic (NM) phase. Then the total density of states and band structures were plotted using GGA and mBJ methods. Since the spin-up and spin-down electrons cut the Fermi energy level, they show metallic properties in the GGA method. Therefore, it is possible to say that CoZrGe half-Heusler compound is a metallic ferromagnetic material when GGA method is used. However, when the mBJ method was used, the band gap was seen around the Fermi energy level in spin up electrons. This showed that spin-up electrons had semiconductor properties and spin-down electrons had metallic nature. Thus, in the mBJ method, CoZrGe half-Heusler compound showed half-metal ferromagnetic nature. The Fermi energy level value in the GGA method was 0.586 Ry, while it was obtained as 0.601 Ry by using the mBJ method. This ensured that the Fermi energy level was higher when the mBJ method was used and the intersections in the GGA method was eliminated. Total magnetic moment is obtained as 1.00 μB/f.u. in both calculation methods. It has been clearly observed that these two different methods affected the Fermi energy level. Finally, CoZrGe half-Heusler compound can be used in spintronic calculations.