Density functional theories study on the properties of Ga1−xCrxAs

The structural, electronic, magnetic and optical properties of Ga 1 − x Cr x As (x = 0, 6.25%, 12.5%) have been studied by first-principles calculations based on the HSE hybrid density functional theories . The optical properties , including the complex dielectric function , optical refractive index , extinction coefficient and absorption coefficient are discussed for radiation up to 15 eV. The results predicate that the system of Ga 1 − x Cr x As exhibits typical half-metallic properties, in which Cr forms deep levels in the forbidden band and reduces the energy gap, increases static dielectric constant and obviously red-shifts the absorption edge . With the increase of the fraction of Cr, the material gradually exhibits noticeable anisotropy in the photon energy range of 0–5 eV. In addition, the p-d hybridization reduces the magnetic moment of Cr from its free space charge value of 3 μ B and a smaller atomic magnetic moments of As and Ga atoms are generated.