Influence of vortex domain walls on magnetoresistance signals in Permalloy rings

Abstract

The magnetization reversal and the corresponding magnetoresistance of Permalloy rings are investigated here both numerically and experimentally. Micromagnetic simulations reveal that during the reversal process there exist three intermediate metastable states which lead to an unconventional triple-switching characteristic. Size effects are studied as well. The simulation results are in good agreement with our magnetoresistance measurements. Significant differences in the magnetoresistance at two orthogonal directions of the magnetic fields are observed and explained. An important contribution to the magnetoresistance due to the relative position of the domains and the current leads is also investigated.