The effect of defects on the electronic and magnetic properties of Co2CrAl Heusler alloy

Ab-initio calculations are performed for antisites, atomic swaps and vacancies point defects in Co2CrAl Heusler alloy. Five defects, namely CrCo, CrAl, AlCo antisites as well as Co–Cr and Cr–Al swap defects exhibit negative formation energies so they may spontaneously occur during the Co2CrAl growth. However, CoCr antisite and Co–Al swap and Cr, Al vacancies defects are unlikely to occur due to their high formation energies. The rest of the defects AlCr and CoAl antisites and Co vacancy defects are very likely to be formed because of the small defect formation energies. The half metallicity is destroyed in the case of CoCr and CoAl antisites as well as Co–Cr and Co–Al swap defects, whereas, the remaining defects retained the half metallicity with band gaps lower than the perfect case.

► Electronic and magnetic structures of perfect and defected Co2CrAl alloy are studied using DFT.
► Perfect structure is totally spin polarized at the Fermi level with a band gap of 0.8 eV.
► CoCr and CoAl antisites as well as Co–Cr and Co–Al swaps destroyed the half metallicity.