Field angle and current density effects in submicrometer spin valves for digital applications

We have characterized the magnetoresistive response of giant magnetoresistive spin valve devices, designed for digital applications, as a function of current density and magnetic field angle. The devices are designed to have only two stable states and are characterized by their positive and negative switching fields. The variations in the switching fields of submicrometer devices are compared with a multilayer single-domain model to determine how accurately the switching fields can be predicted. Significant deviation from single domain behavior is observed. Structure in the magnetoresistive response curve, indicating stable micro-domains, is seen in devices with small line widths and small aspect ratios. At large field angles, the micro-domains are stable to high field values and can dramatically affect the switching process. The variation of the switching fields with bias current and field angle depart considerably from the single domain model predictions