Post-annealing effect on transport properties of CoPd alloy films

Abstract

A series of Co 100− x Pd x (χ=25–85 at.% Pd) alloy films were made by the vapour deposition method. The film thickness t was set at 400 Å. Some of the films were isothermally annealed for 1 h at various temperatures T u in the range 240–400 °C. The average grain size D of each film was checked by an X-ray diffractometer and an atomic force microscope. The zero-field resistivity ρ 0, and the anisotropic magnetoresistance ratio Δρ ρ 0 were measured for each film at room temperature. We have obtained data for D, ρ 0, and Δρ ρ 0 as a function of T u. It is concluded that the 1 h anneals of these films can be divided into two stages: the recovery and the grain growth. It is also found that although the average grain size is enlarged continuously by increasing T u, the transport properties of the films for a fixed thickness approach their saturated values long before the grains stop to grow.