Impact Of Epitaxial Strain On Crystal Field Splitting Of Alpha-Cr2o3(0001) Thin Films Quantified By X-Ray Photoemission Spectroscopy

The influence of epitaxial strain on the electronic structure of alpha-Cr2O3(0001) thin films is probed by combining X-ray photoemission spectroscopy and crystal field multiplet calculations. In-plane lattice strain introduces distortions in the CrO6 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-Cr2O3 thin films.