Magnetization reversal in triangular L10-FePt nanoislands

Triangular FePt nano-islands with size similar to 70 and similar to 330 nm have been prepared by using regular single-layer arrays of nanospheres (173 nm) and microspheres (978 nm), as deposition masks. The coercivity of the 330 nm islands is close to that of the continuous film (11 kOe) whereas the 70 nm ones have coercivity close to 9 kOe and their hysteresis is characterized by the coexistence of an uncoupled soft phase. The switching behavior is characterized by non-zero dM-plots. The lower dM is obtained for the 70 nm sample heat-treated at 500 degrees C for 15 min and increases for longer times and higher heat-treatment temperatures. 10% of the islands are in multi-domain state. These findings are compared with micromagnetic modeling which shows that for anisotropy values high enough to match the observed coercivity, multidomain islands can result in due to the existence of either a softer part or different anisotropy direction part within each magnetic entity. (C) 2013 Elsevier BY. All rights reserved.