Low field giant magnetoresistance in coupled elliptical rings

Abstract

The giant magnetoresistance response of ellipse shaped Co (10 nm) /Cu (8 nm) / Ni80 Fe20 (10 nm) /Cu (2 nm) rings magnetostatically coupled to external magnetic elements has been systematically investigated. Magnetoresistance responses at low field show distinct states when the field is cycled through various intermediate magnetization states of Ni80 Fe20 and Co layers. Due to strong magnetostatic coupling between the ring and the external magnetic elements, these metastable intermediate states were not observed when the field is cycled through saturation. We have also investigated the temperature dependence of magnetization behavior of these rings. Our experimental results are in good agreement with micromagnetic simulations. © 2008 American Institute of Physics.