Current-in-plane magnetoresistance of spin valve elliptical rings

The giant magnetoresistance of Ni Fe ∕ Cu ∕ Co ∕ Ir Mn spin valve elliptical rings with 3.2 ∕ 1.9 μ m major/minor diameter and widths of 340 - 370 nm has been characterized in a current-in-plane geometry. Spin valve rings show asymmetric magnetoresistance curves with three different resistance levels. Minor loop magnetoresistance measurements, which correspond to the switching of only the NiFe free layer, demonstrate that individual control of the chirality of the magnetization vortex in each ferromagnetic layer is possible, enabling at least 16 distinct magnetic configurations to be formed in a spin valve ring.