Ab initio study of Heusler alloys Co2XY (X = Cr, Mn, Fe; Y = Al, Ga) under high pressure

The structural, electronic, and magnetic properties of ferromagnetic Heusler alloys Co2XY (X = Cr, Mn, Fe; Y = Al, Ga) have been investigated by means of the all-electron full-potential linearized augmented plane wave method within the generalized gradient approximation for the exchange and correlation potential. The main focus of this study is to elaborate the changes brought about in the electronic and the magnetic properties by applied pressure. The calculated total spin magnetic moments of all the compounds are found to be in good agreement with experiments. Out of these compounds, Co 2CrAl is found to be perfectly half-metallic (HM) and the other compounds are found to be nearly HM. Thus the HM to metal transition was observed at 75 GPa pressure for Co2CrAl and the nearly half-metal to half-metal transition was observed at 40 GPa and 18 GPa for Co2CrGa and Co2MnAl, respectively, while no transition is observed in other compounds under investigation. It can be clearly seen that pressure affects the minority spin states rather than the majority states, leading to a slight reconstruction of the minority spin states with a shift in the Fermi level driving the above-mentioned transition