PROXIMITY EFFECTS AND CURIE TEMPERATURE ENHANCEMENT IN Co/EuS AND Fe/EuS MULTILAYERS

Abstract

Two identical Co/EuS and Fe/EuS multilayers of six periods each and with individual layers of about 4 nm thick are grown by e-beam evaporation under ultrahigh vacuum conditions. The films show polycrystalline structure with a grain size limited by the individual layer thickness. Both multilayers consist of almost continuous layers with some roughness. The surface peak-to-peak roughness is about 4–5 nm. Magnetization measurements and calculations of the loops based on a Stoner–Wohlfarth-like model allow us to determine the direct antiferromagnetic exchange coupling constant between the 3d metal and EuS at 5 K. Both samples show strong enhancement of the Curie temperature of EuS up to at least 50 K with a EuS magnetization tail, which persists up to about 100 K. The J = 7/2 character of the EuS layers is shown to be responsible for the large Curie temperature enhancement.

Spin Injection From EuS/Co Multilayers Into GaAs Detected by Polarized Electroluminescence

“…However, increasing the size of the quantum wells enables observation of EL in side emission [33]. The easy axis of magnetization in EuS/Co and EuS/Ni systems is known to be located in the sample plane [34]. Thus, measuring the degree of circular polarization of the emitted EL of such a system would enable one to further study EuS/Co systems and would give insights on the degree of electron spin polarization on the injector site and thus the EuS/Co interface.…”