Characterization of epitaxial EuS(111) thin films on BaF2(111) and SrF2(111) substrates grown by molecular beam epitaxy

Abstract

We have successfully grown EuS (111) epitaxial films on BaF2 (111) and SrF2 (111) substrates by using molecular beam epitaxy at substrate temperatures (TS’s) between 100 and 500 °C. Pole figures of X-ray diffraction indicate a high degree of in-plane orientation, and all of the samplesshow very high resistivity. The surface roughness for 10-nm-thick EuS films on BaF2 (111) and SrF2 (111) substrates measured by using atomic force microscopy (AFM) are 0.122 and 0.092 nm, respectively. The Curie temperature of the EuS films increases up to ∼16 K with increasing TS. We also try to manipulate the coercive force, which is an important magnetic property, by Te-doping to achieve an anti-parallel magnetization state between two ferromagnetic layers in spin devices. The obtained coercive force for the Te-doped film (110 Oe) is large compared with that for the undoped one (20 Oe).