Emergence of half-metallic ferromagnetism in Ga1−x Cr x As

Abstract

We have studied the structural, electronic and half-metallic ferromagnetic properties of Ga1−xCrxAs compounds at dopant concentrations x = 0.25, 0.125 and 0.0625. First principle calculations based on density functional theories as implemented in SIESTA code using LDA + U (local density approximation + U) as exchange correlation potential have been used to study the properties of these compounds. Here, U is the Hubbard’s parameter. The calculated results predict that Cr-doped GaAs diluted magnetic semiconductors exhibit half-metallic properties at different concentrations, in which Cr atoms form deep levels in forbidden energy gap. The results also predict that with increase of fraction of Cr atoms, half-metallic energy band gap of Ga1−xCrxAs decreases. Total magnetic moment of these compounds is due to Cr states, and also p–d hybridization between Ga-p and Cr-d induces small magnetic moment on nonmagnetic atoms (Ga and As) for all concentrations.