Electronic structure, magnetic, transport, and optical properties of bulk and film Fe2CrGa Heusler alloy. Effect of structural disorder

Abstract

Magnetic, transport, and optical properties of thin film and bulk [Formula: see text]CrGa alloy samples with different types of atomic order were experimentally investigated. The obtained data were discussed in terms of first-principle calculation results made for the stoichiometric [Formula: see text]CrGa alloy with different types of atomic order and disorder. An ultimate atomic disorder in [Formula: see text]CrGa alloy films was obtained by employing vapor quenching deposition onto substrates cooled by liquid nitrogen. Annealing of as-quenched [Formula: see text]CrGa alloy films causes their crystallization at [Formula: see text] K with the formation of the disordered A2-type structure, which is accompanied by the rapid growth of alloy resistivity in a narrow temperature range, formation of multi-phase magnetic structure and changes in the optical properties. Crystalline bulk and film [Formula: see text]CrGa alloy samples show the dome-like temperature dependence of the resistivity with maximums near their Curie temperatures and explained in terms of competition between negative with temperature contribution from highly resistive media and positive from the electron–magnon scattering. The big resemblance between calculated for [Formula: see text]CuTi type of atomic order and experimental optical conductivity spectra for annealed [Formula: see text]CrGa alloy films proves that [Formula: see text]CuTi type of atomic order is more probable for this alloy.