Domain topology of micro-scale, ferromagnetic pancakes

摘要

Planar, micron-scale ellipses patterned from 700A-thick Co films exhibit nearly complete suppression of hysteresis when magnetized in-plane along their short axes. Using a combination of Magnetic Force Microscopy and Vibrating Sample Magnetometry, we find that the suppression of hysteresis is associated with the continuous deformation of a dipole field configuration. The presence of hysteresis for in-plane, long-axis magnetization is associated with transitions between topologically inequivalent configurations.