Magnetic and electrical properties of spin valve with single and double specular oxide layers

Appropriate oxide capping on a spin valve significantly improved electrical and magnetic properties. The interlayer exchange coupling oscillated in th e thickness range of a Cu spacer (between 20 and 30 Angstrom). The coupling was antiferromagnetic and it allowed us to reduce the Cu spacer down to 20 Angstrom without sacrificing the good properties of the spin valve. The im provement is due to enhanced specular reflection at the interface between t he magnetic and the oxide layer and to less current shunting through the Cu spacer. In particular, the Cu in the capping acts as a filter controlling the diffusion of oxygen, which has led to the soft magnetic properties. Emb edding an additional thin oxide layer into the pinned layer further improve d the magnetoresistance response of the spin valve. Confinement of electron s between two oxides helps increase the occurrence of spin-dependent scatte ring. As a result, high giant magnetoresistance values resulted. The coupli ng oscillated from ferromagnetic to antiferromagnetic as a function of thic kness of the Cu spacer. No significant bias in the coupling was observed an d this lack of bias can be attributed to the smoothness of the interfaces. The oscillations were observable due to amplified Ruderman-Kittel-Kasuya-Yo shida-like coupling by strong reflection at the interfaces of the oxides. ( C) 2001 American Institute of Physics.