Structural, magnetic and electronic properties of non-equilibrium FeAg alloys

Wide concentration ranges of disordered bcc or fcc FeAg alloys have been produced by sputter-deposition. They are ferromagnetic at low temperatures. The average hyperfine field and the magnetic moment of Fe atoms are larger than those of pure Fe, because the substitution of Fe by Ag with a larger atomic size expands the atomic volume of Fe and enhances the spin polarization. In fcc FeAg alloys, the quadrupole splitting analysis of Mössbauer spectra indicates no remarkable segregation in the as-sputtered state, while it shows a continuous growth of fcc Fe clusters by aging and a phase transformation to bcc by annealing above 520 K. X-ray photoemission spectroscopy studies of these alloys reveal individual Fe and Ag peaks. The concentration dependence of peak intensities and peak positions indicate that Fe and Ag electronically intermix.