The Effects Of Doped Interfaces On Magnetoresistance And The Anomalous Magneto-Optical Kerr Effect In A Co/NiO/Cu/Co/Cu Structure

Giant magnetoresistance (GMR) has been widely used in many technical applications, such as in industrial sensors, hard disk read heads, magnetic random ac-cess memory and digital circuit isolators. The interface doping plays a critical role in determining GMR, due to the spin-dependent scattering of conductance electrons at interface. This dissertation addresses the effects of doping with nano-nitride-layer (NNL) at the interfaces in the two structures: Cu/Co/Cu/Co/Cu and NiO/Co/Cu/Co/Cu.(a) In the structure of Cu/Co/Cu/Co/Cu, as the NNL is doped at one of the two inner interfaces of the core sandwich Co/Cu/Co, an inverse magnetoresistance (MR) is observed due to the negative spin asymmetry induced by the NNL, which is theoretically testified by the GMR calculation using semiclassical Boltzmann transport model. As the two inner interfaces of the core Co/Cu/Co sandwich are doped with the NNL at the same time, the inverse MR can also be observed because of difference in scattering spin asymmetry at the two doped interfaces, which is indi-cated in the low-angle X-ray reflectivity measurement. When the two outer interfaces between the core sandwich (Co/Cu/Co) and the buffer or/and the capping layers are doped with the NNL, all doped samples exhibited the reduced normal MR, quite dif-ferent from the inner doped ones, indicating that the positions of the NNL doping play a critical role in MR.