Electronic structures and magnetic properties of a II-II-V based diluted magnetic semiconductor Ba1−xKx(Cd1−yMny)2As2 with decoupled charge and spin doping

Abstract

By using the density functional theory within Perdew–Burke–Ernzerh of generalized gradient approximation, the electronic structures and magnetic properties of system were investigated. Undoped compound is a semiconductor crystallized with a hexagonal −type structure. After local moments doping via isovalent (Cd2+, Mn2+) substitutions, is antiferromagnetic system, which is attributed to the superexchange interactions between the Mn2+ ions in the high spin state. With itinerant holes introduced via off-stoichiometry (Ba2+, ) substitutions, system (except for the system doped with the most nearest neighbor Mn-Mn pair) changes from antiferromagnetic to ferromagnetic, resulted from the indirect exchange interactions based on p − d exchange coupling between As and Mn orbitals. Moreover, hypothetical supercells with different lattice parameters under mechanical compression and expansion were calculated to study the effect of itinerant holes on the Curie temperature. Our results reveal that the system with small lattice has more holes amount and better holes mobility, leading to a higher Curie temperature for the -type structure DMSs.