Effect of Co impurity layers on the AMR enhancement of Ni thin films

Abstract The transport properties of Ni thin films with Co and Cu impurity layers were studied as a function of the distance between the impurity layers. The films were fabricated by DC magnetron sputtering and the nominal thickness was kept constant at 1500 A. Co and Cu impurity layers were inserted into the films using deposition times insufficient to fill one atomic layer. The distance between these layers, L , was varied from 10 to 500 A. In the case of Ni films with Co impurity layers, the anisotropic magnetoresistance (AMR) increases significantly with decreasing L , and approaches the value of the Ni mean free path. At 20 K, the longitudinal MR is 1.3% for pure Ni films and increases to 1.8% and 2.8% when L = 40 and 10 A, respectively. A much lower effect has been observed in the case of Cu, and this indicates the importance of the magnetic nature of the impurity interface layers in the enhancement of MR.