Metallic and half-metallic properties of full Heusler alloy Co2MnGa with antisite defects

Heusler compounds are attracting tremendous attention due to their significant magnetoresistance, half-metallicity, and other properties which are used in spintronics, magnetooptical, memory devices, etc. [1]. We performed first-principal calculations for compound Co₂MnGa, taking into consideration antisite structural defects. Co₂MnGa without antisite defects was confirmed to be a topological Weyl compound. The exact electronic states at E Fermi are 1.8 st./eV/f.u. in the majority spin and 0.58 st./eV/f.u. in the minority spin. Hence, the spin polarization is 52%. The magnetic moments are 0.73 (Co) μ_B, 2.91 (Mn) μ_B and -0.15 (Ga) μ_B, and the total moment of Co2MnGa is 4.22 μ_B, which is in good agreement with the experimentally reported moment of 4.05 μ_B, which corresponds to the accuracy of our theoretical calculation being as high as 96%, it was previously calculated to be between 3.07 and 4.21 μ_B [1]. For the Co1-Mn antisite defect, the magnetic moment decreases to 1.07 μ_B; for the Co2-Ga replacement, the magnetic moment is 1.85 μ_B. However, for the Co2-Mn antisite replacement, the total magnetic moment reaches up to 5.89 μ_B. Thus, the antisite defects in Co₂MnGa result in different changes in the magnetic moments and metallic properties, following from the densities of electron states calculated in our study.

1. Elphick, K.; Frost, W.; Samiepour, M.; Kubota, T.; Takanashi, K.; Sukegawa, H.; Mitani, S.; Hirohata, A. Heusler alloys for spintronic devices: review on recent development and future perspectives. STAM 2021, 22, 1, 235–271.https://doi.org/10.1080/14686996.2020.1812364