Ab-initio investigations of structural, electronic, magnetic and optical properties of ferromagnetic Cd1–xMnxTe

We report ab-initio calculations of the structural, electronic, magnetic and optical properties of the alloy Cd1–xMnxTe 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 Cd1–xMnxTe 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 Cd1–xMnxTe. The spin-exchange splitting energy Δx(d) increases with increasing ‘x’ in Cd1–xMnxTe and the values of p–d exchange splitting energy Δx(pd) of Cd1–xMnxTe show that the effective potential for the minority spin is more attractive than that for the majority spin. The values of exchange constants N0α and N0β obtained for Cd1–xMnxTe are in agreement with the reported data. The magnetic moment per Mn atom reduces from its free space charge value of 5μB to around 4μB 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 Cd1–xMnxTe.