Mossbauer spectroscopic study of ion beam mixing at Fe-Cu interface

Abstract

Metastable FeCu alloy films have been synthesized by ion beam induced atomic mixing at the Fe-Cu interface. Polycrystalline copper foils coated with 180 λ thick overlayer of iron (enriched to ˜33% in the concentration of ⁵⁷Fe mossbauer isotope) have been, bombarded with Kr⁺ ions having energies in the range between 30 keVand 120 keV at a dose of -10¹⁶ions/cm². The as-deposited and ion beam mixed composites have been characterized by using the submicron sensitive technique of conversion electron mossbauer spectroscopy (CEMS). The ion energy dependence of the extent of mixing has been compared with model calculations of energy deposition in interface layers. By deconvoluting the complex mossbauer spectra it has been shown that interface alloy formed by ion mixing exhibits the presence of a random chemical disorder. The ferromagnetic spectral contributions have been analyzed in terms of the presence of one or more copper atoms (acting as magnetic holes in the near neighbour shells of the ⁵⁷Fe atoms).