Field orientation dependence of magnetoresistance in spin-dependent tunnel junctions

The dependence of magnetotransport on field orientation is an important issue in spintronics-related devices where the applied field is not necessarily in the ideal field-in-plane (FIP) geometry. In this study, we perform tunneling magnetoresistance (TMR) measurements on Co-Al/sub 2/O/sub 3/-CoFe-NiFe spin-dependent tunnel (SDT) junctions prepared at different conditions with varying field orientation ranging from FIP to field-perpendicular-to-plane (FPP). The TMR ratio decreases drastically, whereas the switching field of Co increases when the field direction is set close to FPP. Furthermore, in a situation near FPP, a peculiar TMR looping behavior is observed for one set of samples. Interface effect is thought to be related.