Multiplicity of magnetic domain states in circular elements probed by photoemission electron microscopy

Abstract

A systematic study of the remanent magnetic states in Co and Ni80Fe20 disks 1.65μm in diameter with varying film thickness (5-38nm) imaged by a noninvasive imaging technique (namely, photoemission electron microscopy) is presented. The magnetic configurations observed range from the vortex state, to other well defined multidomain states, namely a state with two vortex cores ("diamond" state) and a high remanence "triangle" state, which are mapped according to material and thickness range. In most instances, more than one magnetic state coexist in different disks of the same array, subjected to the same field history. These observations are correlated with magneto-optical Kerr effect measurements and micromagnetic simulations to show that the observed magnetic metastable states are stabilized by defects or attained in the nucleation process following the removal of the applied magnetic field. © 2005 The American Physical Society.