Influence of interface structure of Co/Cu (100) superlattices on electronic structure and giant magnetoresistance

Electronic structures and magnetoresistance (MR) of Co3Cu5 and Co3Cu7 models as well as their interface atom exchange models Co2CuCoCu4 and Co2CuCoCu6 are investigated by the first-principles pseudopotential plane-wave method based on density functional theory. Charge transfer, magnetic moment, density of states, spin asymmetry factor, and MR ratio are discussed. the result show that the values of charge transfer and spin asymmetry factor at the Fermi level of Co layers are closely related to the neighbouring background of the Co layer. The Co layer with two sides adjacent to the Cu layer would transfer more charge to the Cu layer than other neighbouring background and have the largest spin asymmetry factor at the Fermi level. The Co layer with two neighbouring Co layers (interior Co) would gain a little charge and have the smallest spin asymmetry factor at the Fermi level. two-current model is used to evaluate the MR ratio of Co2CuCoCu4 (Co2CuCoCu6) to be larger than that of Co3Cu5 (Co3Cu7), which can be explained by the charged transfer and spin asymmetry factor.