Study on the interfacial characterization of the Co_5/Cu_3/Co_5 trilayer and Co_3/Cu/Co/Cu_3/Co/Cu/Co_3 multilayer

摘要

Comprehensive results are presented on the influence of interfaces on electronic structure and giant magnetoresistance (GMR). Two structures were calculated for Co_5/Cu_3/Co_5 and Co_3/Cu/Co/Cu_3/Co/Cu/Co_3, where numbers stand for monolayer numbers of atoms, by employing the discrete variational method in the framework of the local spin density approximation. It has been found that the electron spin-dependent scattering is very strong at the interfaces compared to the interiors of the ferromagnetic layers, independent of the moment alignment configuration. The calculation results of total energy for various magnetization configuration revealed that antiferromagnetic exchange coupling was present between any of the ferromagnetic layers separated by Cu layers at zero field in the Co_3/Cu/Co/Cu_3/Co/Cu/Co_3. The evaluated GMR ratio for the Co_3/Cu/Co/Cu_3/Co/Cu/Co_3 (about 35.1 percent) was much larger than that of the Co_5/Cu_3/Co_5 (about 21.0 percent), indicating large GMR effect could be expected with more interfaces when the thicknesses were the same. The result also indicated that the negative polarization of 4s electrons could reduce the GMR effect.