Growth and Characterisation Studies of Eu$_3$O$_4$ Thin Films Grown on Si/SiO$_2$ and Graphene

Abstract

We report the growth, structural and magnetic properties of the less studied Eu-oxide phase, Eu 3 O 4 , thin films grown on a Si/SiO 2 substrate and Si/SiO 2 /graphene using molecular beam epitaxy. The X-ray diffraction scans show that highly-textured crystalline Eu 3 O 4 (001) films are grown on both substrates, whereas the film deposited on graphene has a better crystallinity than that grown on the Si/SiO 2 substrate. The SQUID measurements show that both films have a Curie temperature of 5.5 ± 0.1 K, with a magnetic moment of 0.0032 emu/g at 2 K. The mixedvalency of the Eu cations has been confirmed by the qualitative analysis of the depth-profile Xray photoelectron spectroscopy measurements with the Eu 2+ : Eu 3+ ratio of 28 : 72. However, surprisingly, our films show no metamagnetic behaviour as reported for the bulk and powder form.Furthermore, the Raman spectroscopy scans show that the growth of the Eu 3 O 4 thin films has no damaging effect on the underlayer graphene sheet. Therefore, the graphene layer is expected to retain its properties.