Half-Metallic Properties of Mn-AlN and Cr-AlN Based on First-Principles

Abstract

The band structures,density of states(DOS),and magnetic properties of wurtzite Mn-AlN and Cr-AlN were studied using density functional theory(DFT) with the generalized gradient approximation(GGA) for the exchange-correlation potential.The results indicate that the half-metallic gap of Mn-AlN and Cr-AlN decreases as the Mn/Cr doping concentration increases.This probably results from an increase in the interaction between Mn and Mn or Cr and Cr atoms and a decrease in the hybridization of Mn/Cr 3d and N 2p states with increasing the Mn/Cr doping concentration,which results in a smaller spin-exchange splitting so the half-metallic gap is reduced.Additionally,with the same doping concentration,the half-metallic gap of Mn-AlN is larger than that of Cr-AlN.This is due to the lower Mn 3d states compared to the Cr 3d states and the hybridization of Mn 3d and N 2p states being stronger in Mn-AlN,which leads to a larger spin-exchange splitting so the conduction band minimum of the down spin bands moves far away from the Fermi level and the half-metallic gap of Mn-AlN becomes larger.