Growth and Characterisation Studies of Eu$_3$O$_4$ Thin Films Grown on Si/SiO$_2$ and Graphene
| Autor: | Aboljadayel, R. O. M., Ionescu, A., Burton, O. J., Cheglakov, G., Hofmann, S., Barnes, C. H. W. |
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| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | Nanomaterials 2021, 11(6), 1598 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.3390/nano11061598 |
| Popis: | 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 about 5.5 K, with a magnetic moment of 0.0032 emu/g at 2 K. The mixed-valency of the Eu cations has been confirmed by the qualitative analysis of the depth-profile X-ray 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. Comment: 16 pages, 9 figures |
| Databáze: | arXiv |
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