Magnetic and structural properties of Cr-based diluted magnetic semiconductors and alloys

We applied supercell approach by using local spin density functional theory for Cr-doped GaN, CrN/ScN superlattices and the linear muffin-tin orbital method to predict the structural and magnetic properties of these novel diluted magnetic semiconductors (DMS), superlattices and their CrxSc1−xN alloys. The global energy minimum of CrN is obtained for rocksalt (RS) structure if the compound is expanded by 8% and the phase becomes stable in the ferromagnetic (FM) state. The global energy minimum for the stable state occurs at in-plane lattice constant of 3.9 Å. In addition, the structural and optical properties of single crystal CrN/ScN superlattices and Cr1−xScxN alloys are studied in detail. We report an isostructural phase transition from wurtzite (w-CrN) to hexagonal (h-ScN) at a hydrostatic pressure of 21 GPa which is associated with anomalous optical and piezoelectric properties.