Energy barrier versus switching field for patterned Co_(80)Pt_(20) alloy and Co/Pt multilayer films

摘要

Two Co/Pt multilayer samples have been fabricated with a difference in the number of bilayers, leading to a total magnetic layer thickness of 3 nm and 20 nm. From these films, large arrays of magnetic islands have been patterned using laser interference lithography and ion beam etching. We have investigated the switching field distribution (SFD) of approximately 80 islands and thermal switching field distribution SFD_T of individual islands of both samples using the anomalous Hall effect. We compare the results of these measurements with the (SFD_T) of a previously investigated alloy with a magnetic layer thickness of 20 nm by comparing the results of over 1000 hysteresis loops of a single weak island and a single strong island. We found that that the energy barrier for the multilayer islands increases with increasing switching field, whereas it was previously found that the energy barrier for the alloy stays constant with varying switching fields. When comparing the two multilayer samples, we observe that the grain size, anisotropy, and switching field distribution are more or less independent on thickness, whereas the switching field at both 0 K and 300 K decreases with film thickness.