Mechanism of coercivity in epitaxial SmCo5 thin films

The magnetization reversal mechanism in pulsed laser deposited, hard magnetic epitaxial SmCo5 thin films with high coercivity (> 3 T) and remanent polarization (0.94 T) is investigated. From temperature and angle dependent hysteresis measurements in the framework of the micromagnetic model, we show that the magnetization reversal is described by a hindered domain wall movement. This conclusion from a global analysis is supported by magnetic force microscopy, by imaging the domain evolution in the magnetization process. The smallest stable magnetic entity is found to be of the order of 150 nm. The excessive number of grain boundaries due to the nanometer length scale of the grain size, in addition to possible defects within the grains, is expected to be the key to the excellent magnetic properties and the observed magnetization reversal mechanism.