Magnetization evolution in microstructured Permalloy ellipses

Summary form only given. The advances in nanolithography and new techniques in probing magnetic domain structures such as magnetic force microscopy (MFM) have given scientists an unprecedented way towards the understanding of micromagnetism. We present results of magnetic domain configurations probed at remanent states as well as under external magnetic fields in microstructured Permalloy thin films. Special interest is focused on the formation and evolution of vortex states in elliptical elements. Various ellipses were delineated using standard electron beam lithography, followed by a thermal evaporation of permalloy in the absence of an external magnetic field. The patterned films were then transferred onto a SiN-coated Si-substrate through a lift-off process in acetone. A magnetic force microscope equipped with an external electromagnet was used to investigate the magnetization configurations.