Influence of a structural transition on the optical and the magneto-optical properties of Co2MnGa alloy films

Co2MnGa Heusler alloy (HA) films with significantly different structural orders were fabricated, and the influence of atomic ordering on various physical properties was investigated. Co2MDGa films were deposited by flash evaporation onto glass substrates at various substrate temperatures from 150 to 753 K. A disordered state of the films was achieved by vapor-quenching deposition at 150 K. The structural disorder of the films was found to lead to a loss of ferromagnetism and to changes in the optical and the magneto-optical properties. Also, neither the deposition or post-annealing below 728 K was found to lead to full crystallization with a L2(1) structure. Comparison of the experimental optical properties with theoretical calculations based on the full-potential linearized-augmented-plane-wave (LAPW) method shows a big discrepancy, so a more elaborated calculation method is thought to be required.