Inverse magnetoresistance caused by nano-nitride-layer doping at the inner interfaces in the sandwich of Co∕Cu∕Co

The influence of a nano-nitride-layer (NNL) doped at different interfaces in the structure of Cu∕Co∕Cu∕Co∕Cu on magnetoresistance (MR) is investigated. As the NNL is doped at the inner interfaces of the core Co∕Cu∕Co sandwich, an inverse MR is observed. This contrasts sharply with that doping at the two outer interfaces between the core sandwich (Co∕Cu∕Co) and the buffer or/and the capping layers. The result arises from the negative spin asymmetry induced by the NNL doping under different interfacial circumstances. Moreover, the MR value increases in magnitude as temperature is decreased from room temperature to 4.2K.