Band Structure of Dilute Metastable Co-Ag Alloys

Abstract

Co—Ag systems have recently attracted considerable attention in application oriented research of ferromagnetic thin films and multilayers. Due to low miscibility of Ag in Co it is easy to fabricate thin Co-Ag films of granular structure, promising as a high magnetoresistance material. It was also shown that using modern technology it is possible to deposit thin films of Co—Ag forming metastable homogeneous alloys for compositions far exceeding the solubility limit. In the present paper results of electronic structure calculations by the tight-binding linear muffin-tin orbital method are reported. Computations were done for hypothetical uniform ordered Co 100-x Ag xalloys assuming proper extended unit cells to simulate concentrations of x = 25, 12.5, 6.25, 3.125 at.%. The results were used to calculate the photoemission spectra. The calculated photoemission spectra are in fair agreement with experimental data supporting the conclusion of existence of a homogeneous though metastable alloy in the dilute limit. On the contrary, superposition of pure Co and Ag spectra implied for precipitate of Ag in Co cannot explain the experimental data.