Ab-initio investigations of structural, electronic, magnetic and optical properties of ferromagnetic Cd 1– xMn xTe

Abstract

We report ab-initio calculations of the structural, electronic, magnetic and optical properties of the alloy Cd 1– x Mn x Te as a function of the Mn concentration ‘ x’. Ab-initio calculations are based on the density functional theory (DFT) within the generalized gradient approximation (GGA). The calculated lattice constants of the Cd 1– x Mn x Te alloys exhibit Vegard's law downward bowing parameter. For the minority spin channel the Fermi level shifts toward higher energy with the value of ‘ x’ in Cd 1– x Mn x Te. The spin-exchange splitting energy Δ x (d) increases with increasing ‘ x’ in Cd 1– x Mn x Te and the values of p–d exchange splitting energy Δ x (pd) of Cd 1– x Mn x Te show that the effective potential for the minority spin is more attractive than that for the majority spin. The values of exchange constants N 0 α and N 0 β obtained for Cd 1– x Mn x Te are in agreement with the reported data. The magnetic moment per Mn atom reduces from its free space charge value of 5μ B to around 4μ B due to p–d hybridization and this results into an appearance of small local magnetic moments on the non-magnetic Cd and Te sites. The absorption threshold shifts toward higher energy and the static refractive index decreases with the increasing value of ‘ x’ in Cd 1– x Mn x Te.