Investigations of the electronic and magnetic structures of Co2YGa (Y=Cr, Mn) Heusler alloys and their (100) surfaces

Density functional theory calculations are performed to investigate the structural, electronic, and magnetic properties of bulk structures of Co2YGa (Y = Cr, Mn) Heusler alloys and the surfaces along the (100) orientation. The bulk structures of both alloys show a ferromagnetic behavior with total magnetic moments of 3.03μB and 4.09μB and high spin polarizations of 99% and 67% for Co2CrGa and Co2MnGa, respectively. The surfaces are found to exhibit corrugations due to different relaxations of the surface atoms. For the case of Co2CrGa, two surfaces preserve the half metallicity, namely those with Cr-Ga and Ga– terminations with high spin polarizations above 90%, whereas it dropped to about 50% for the other surfaces. However, the spin polarizations of Co-Co and Mn-Ga terminated surfaces remain close to that of bulk Co2MnGa alloy, whereas it is suppressed down to 17% for Co– termination. The highest local magnetic moments are found to be 3.26 μB and 4.11 μB for Cr and Mn surface atoms in Cr-Ga and Mn– terminated surfaces, respectively