The structural-phase state and magnetoresistive properties of thin film alloys obtained by co-evaporated Cu and Co

•The influence of the structural phase state on the MR properties was studied.•The annealing leads to increase the values of magnetoresistance and coercive force.•At a concentration of CCo ≥ 50 at% an anisotropic magnetoresistance has been observed.•The maximum value of GMR in the as-deposited state was observed at the CCo = 21 at%. This research presents the study on the structural-phase states and magnetoresistive properties of thin nanogranular film alloys based on Cu and Co with a total concentration of Co in the range of 15 ≤ x ≤ 71 at%. The analyses for the unannealed and annealed thin films with a thickness d = 20 nm, have been performed. The films have been annealed in the temperature range from 300 to 800 K for 20 min. It found that the heat treatment within the range from 600 to 800 K led to an increase in the magnetoresistance and coercive force due to the growth of Co granules size under heat treatment and partial decomposition of the fcc-Cu(Co) solid solution. The highest magnitudes of the magnetoresistance were found in the as-deposited film alloys featured by the total concentration of Co x = 21 at%, which consist of Cu(Co) solid solution made of fcc-Cu and superparamagnetic Co granules (size L = 2 ÷ 5 nm). Interestingly, the thin film alloys with an increased concentration of Co x ≥ 50 at% exhibited anisotropic magnetoresistance.