Thickness and composition dependences of magnetic and magnetoresistive properties of CoxAg100-x alloys thin films

•The influence of the structural phase state and thickness of granular films on the MR properties were studied.•The MR ratio increases with increasing of films thickness.•The structural percolation threshold depends on the thickness of the granular film.•Calculations based on the Livenstein percolation theory are agreed with experimental results. In granular thin films consisting of small particles of magnetic metal dispersed in nonmagnetic matrix both magnetization and magnetoresistance phenomena are directly related, and their relationship is very complex. This is due to the distribution of ferromagnetic grains in nonmagnetic metallic matrix and its mutual magnetic interactions. In this paper, we studied influence of CoxAg100-x film composition and thickness on film structure, magnetization and magnetoresistance. It has been found that the size of Co grains correlates with the sample thickness for the films withd = 20 nm, and the superparamagnetic state of Co granules is preserved up to x ≤ 55 at.%. However, thicker samples are superparamagnetic only up to x