Electronic structure and magnetic properties of Fe₂YSi (Y = Cr, Mn, Fe, Co, Ni) Heusler alloys: a theoretical and experimental study

Abstract

A series of Fe2YSi (Y = Cr, Mn, Fe, Co, Ni) alloys were synthesized and their electronic and magnetic properties were studied both theoretically and experimentally. In particular, a novel Heusler alloy Fe2CrSi single phase was synthesized by means of the melt-spinning method. First principles FLAPW calculations were performed on Fe2YSi alloys. Based on the results, Fe2CrSi is predicted to be a half-metallic ferromagnet with a spin moment of 2?B/f.u. and a gap of 0.42?eV. Fe2MnSi is also half-metallic in the ferromagnetic state. The saturation magnetic moments at 5?K for this series of alloys fit the theoretical calculations well. Specifically, the saturation magnetic moment of Fe2CrSi is 2.05?B/cell, which agrees with the ideal value of 2?B derived from the Slater?Pauling rule. The Curie temperatures of Fe2YSi alloys are all higher than 500?K except for Fe2MnSi, which has a TC below room temperature. Finally, the effect of lattice distortion on the electronic and magnetic properties of Fe2CrSi and Fe2CoSi was studied. It is found that Fe2CrSi is half-metallic from ?3% to +1% uniform lattice distortion, and this character is preferred in systems containing large strain, such as melt-spun ribbons or thin films.