Impact of epitaxial strain on crystal field splitting of $\alpha$-Cr$_2$O$_3$(0001) thin films quantified by X-ray photoemission spectroscopy

Pâmella Vasconcelos Borges Pinho (1, 2) , Alain Chartier (1) , Frédéric Miserque (3) , Denis Menut (4) , Jean-Baptiste Moussy (2, 5)

1 LM2T - Laboratoire de Modélisation, Thermodynamique et Thermochimie
2 LNO - Laboratoire Nano-Magnétisme et Oxydes
3 SCCME - Service de la Corrosion et du Comportement des Matériaux dans leur Environnement
4 SSOLEIL - Synchrotron SOLEIL
5 SPEC - UMR3680 - Service de physique de l'état condensé

The influence of epitaxial strain on the electronic structure of $\alpha$-Cr$_2$O$_3$(0001) thin films is probed by combining X-ray photoemission spectroscopy and crystal field multiplet calculations. In-plane lattice strain introduces distortions in the CrO$_6$ octahedron and splits the 3d orbital triplet t$_2g$ into a$_1$ + e orbitals. For relaxed thin films, the lines-shape of the Cr 2p core levels are well reproduced when the t$_2g$ subset is fully degenerated. In-plane tensile strain stabilizes a$_1$ with respect to e orbitals, whereas compressive strain destabilizes a$_1$ orbitals. Understanding these crystal field variations is essential for tuning the physical properties of $\alpha$-Cr$_2$O$_3$ thin films.

Mots clés: Cr$_2$O$_3$; crystal field splitting; epitaxial strain; X-ray photoemission spectroscopy; crystal field multiplet calculations

Domaines: Physique [physics]; Matériaux

Pâmella Vasconcelos Borges Pinho, Alain Chartier, Frédéric Miserque, Denis Menut, Jean-Baptiste Moussy. Impact of epitaxial strain on crystal field splitting of $\alpha$-Cr$_2$O$_3$(0001) thin films quantified by X-ray photoemission spectroscopy. Materials Research Letters, 2021, 9, pp.163-168. ⟨10.1080/21663831.2020.1863877⟩. ⟨cea-03135636⟩