An investigation of semiconducting behavior in the minority spin of Co2CrZ (Z = Ga, Ge, As): LSDA and LSDA + U method

We have calculated the electronic and magnetic properties of 3d transition metal based full Heusler compounds Co2CrZ (Z = Ga, Ge, As), by using full potential linearized augmented plane wave (FP-LAPW) method. The calculated density of states (DOS) and band structure for Co2CrZ shows the existence of band gap in their minority-spin channel. The respective energy gaps of Co2CrGe and Co2CrGa are 0.24 and 0.38 eV with their Fermi energies (EFs) lie exactly at the gap. The compound Co2CrAs when treated with local spin density approximation (LSDA) does not show half metallic ferromagnetism (HMF) even though there exist a gap this is because the EF does not lie at the middle of the gap. We have considered Co2CrAs as strongly correlated system as Cr-d states at EF are strongly localized thus the system was treated in terms of the LSDA + U. The total magnetic moment of Co2CrAs was found to be an exact integer value 5.00 μB within LSDA + U. We have also found that the total magnetic moments increase as the Z goes from Ga to As.

► Volume optimization was done to find the theoretical lattice parameters. ► LSDA was performed to calculate electronic and magnetic properties of Co2CrZ. ► The result shows the half-metal ferromagnetic behavior of Co2CrGa and Co2CrGe. ► Co2CrAs fails to give HMF within LSDA thus treated with LSDA + U, to obtain HMF.