Film thickness dependence of the enhanced EuS interface ordering temperature in EuS∕Co thin films

Abstract

The temperature dependent magnetism of EuS(tnm)∕Co(tnm) films, where t=3.5, 5.0, 7.8, and 20nm, reveals two EuS ordering temperatures TC: one magnetic phase order below TC∼16K that corresponds to pure EuS and the other phase order at a TC>200K that has a EuS thickness dependence. This enhanced TC is the result of EuS interface moments exchanged coupled to Co moments in an antiparallel configuration. The interface TC varies with inverse EuS film thickness, a behavior that is consistent with a magnetic proximity effect, and the amount of EuS that orders at the enhanced TC decreases with film thickness, t<10nm.