Solid State Amorphisation in Magnetic Multilayers: the Interface Structure and the Electrical Transport Properties

The structure and electrical conductivity properties of the R.F. sputtered FeZr and FeTi multilayers with ultrathin layer thicknesses, in as-deposited states, have been studied using X-ray diffraction, low-angle X-ray and neutron reflectometry, conversion electron Mössbauer spectroscopy (CEMS), resistivity and magnetoresistivity measurements. The thickness ratio (β=d_Fed_Zr and d_Fed_Ti) of analysed multilayers was 0.5 and 1, the values of the bilayer thickness (λ=d_Fe+d_Ti,Zr) was varied from 9 Å to 600 Å, maintaining constant the total thickness of the samples by controlling the number of bilayers. The results obtained from CEM-spectroscopy and X-ray diffraction show that Fe layers of the thickness below 20 Å are alloyed forming an amorphous phase during deposition. This amorphous phase is distributed in the plane between the crystalline sublayers as well as in the grain boundaries according with the proposed model of the interpretation of the electrical conductivity as a function of the bilayer thickness (λ).