Perpendicular and in-plane hole asymmetry in a strained NiFe 2 O 4 film

• Published in: Journal of physics. Condensed matter 2021-06, Vol.33 (22), p.225801
• Main Authors: Knut, R, Malik, R S, Kons, C, Shoup, J E, Radu, F, Luo, C, Kvashnin, Y O, Gupta, A, Karis, O, Arena, D A
• Format: Article
• Language: English
• ISSN: 0953-8984; 1361-648X; 1361-648X
• DOI: 10.1088/1361-648X/abf0c5

Strained materials can exhibit drastically modified physical properties in comparison to their fully relaxed analogues. We report on the x-ray absorption spectra (XAS) and magnetic circular dichroism (XMCD) of a strained NiFe O inverse spinel film grown on a symmetry matched single crystal MgGa O substrate. The Ni XAS spectra exhibit a sizable difference in the white line intensity for measurements with the x-ray electric field parallel to the film plane (normal incidence) vs when the electric field is at an angle (off-normal). A considerable difference is also observed in the Fe XMCD spectrum. Modeling of the XAS and XMCD spectra indicate that the modified energy ordering of the cation 3 states in the strained film leads to a preferential filling of 3 states with out-of-plane character. In addition, the results point to the utility of x-ray spectroscopy in identifying orbital populations even with elliptically polarized x-rays.