Improved half-metallic gap of zincblende half-metal superlattices with the Tran–Blaha modified Becke–Johnson density functional

•The total magnetic moment follows a Slater–Pauling-like “rule of 8”.•The mBJ half-metallic gaps are enhanced compared to GGA results.•When the SOC is included, they show a very high spin polarization (greater than 98%).

Binary transition-metal pnictides and chalcogenides half-metallic ferromagnetic materials with zincblende structure, being compatible with current semiconductor technology, can be used to make high-performance spintronic devices. Here, we investigate electronic structures and magnetic properties of composite structure ((CrX)2/(YX)2(CrX)2/(YX)2 (X=As, Sb; Se, Te and Y=Ga; Zn) superlattices) of zincblende half-metallic ferromagnetism and semiconductor by using Tran and Blaha's modified Becke and Johnson (mBJ) exchange potential. Calculated results show that they all are half-metallic ferromagnets with both generalized gradient approximation (GGA) and mBJ, and the total magnetic moment per formula unit follows a Slater–Pauling-like “rule of 8”. The key half-metallic gaps by using mBJ are enhanced with respect to GGA results, which is because mBJ makes the occupied minority-spin p-bands move toward lower energy, but toward higher energy for empty minority-spin Cr-d bands. When the spin–orbit coupling (SOC) is included, the spin polarization deviates from 100%, and a most reduced polarization of 98.3% for (CrSb)2/(GaSb)2(CrSb)2/(GaSb)2, which indicates that SOC has small effects, of the order of 1%, in the considered four kinds of superlattice.

Graphical abstractThe mBJ half-metallic gaps (GhmGhm) are enhanced compared to GGA results for these zincblende half-metal superlattices.Figure optionsDownload full-size imageDownload as PowerPoint slide