Femtosecond Laser Pulse-Induced Perpendicular Magnetization in Co Ultrathin Films With Diverse Surroundings

Laser-induced irreversible modifications of magnetic properties of molecular beam epitaxy grown X/Co/Y trilayers on Al2O3 substrates were investigated, with combinations of nonmagnetic metals Pt and Au as buffer X and capping layer Y. It is shown that the formation of regions with irreversibly rotated magnetization from in-plane to out-of-plane orientation occurred for Pt/Co/Pt, Pt/Co/Au, and Au/Co/Pt trilayers. In the Au/Co/Au system, the modification of magnetic properties was negligible. Pt/Co/Pt trilayers were also deposited by sputtering on Si/SiO2 substrates. In this case, a significant suppression of laser-induced magnetic modifications was observed and correlated with the lower thermal conductivity of the Si/SiO2 substrate.