CPP-GMR Film With ZnO-Based Novel Spacer for Future High-Density Magnetic Recording

Abstract

A new type of CPP-GMR film, which has ZnO-based novel spacer, was studied. A high MR ratio of 21.4% at RA of about 0.2 ¿¿m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at room temperature was obtained by optimization of the fabrication condition of ZnO layer. Based on HRTEM observation, the ZnO spacer is crystalline which have c-axis orientation with wurtzite structure, and there are no metallic portions. The measured noise is in good agreement with Johnson noise fitted at T = 400(K). This result suggests that the contact at our ZnO-based spacer interface with magnetic electrode is ohmic. First principle calculations that used a simple model supported the existence of large spin dependent scattering at the interface of ZnO layer. These results indicate that higher signal to noise ratio can be achieved in this type of CPP GMR head even with lower MR ratio than MTJ head and it is very attractive candidate of future magnetic read sensor in HDDs.