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arXiv · 1011.4818

Orbital occupation and magnetic moments of tetrahedrally coordinated iron in CaBaFe4O7

N. Hollmann·Z. Hu·Hua Wu·M. Valldor·N. Qureshi·T. Willers·Y. -Y. Chin·J. C. Cezar·A. Tanaka·N. B. Brookes·L. H. Tjeng
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Abstract

CaBaFe4O7 is a mixed-valent transition metal oxide having both Fe2+ and Fe3+ ions in tetrahedral coordination. Here we characterize its magnetic properties by magnetization measurements and investigate its local electronic structure using soft x-ray absorption spectroscopy at the Fe L2,3 edges, in combination with multiplet cluster and spin-resolved band structure calculations. We found that the Fe2+ ion in the unusual tetrahedral coordination is Jahn-Teller active with the high-spin e^2 (up) t2^3 (up) e^1 (down) configuration having a x^2-y^2-like electron for the minority spin. We deduce that there is an appreciable orbital moment of about L_z=0.36 caused by multiplet interactions, thereby explaining the observed magnetic anisotropy. CaBaFe4O7, a member of the '114' oxide family, offers new opportunities to explore charge, orbital and spin physics in transition metal oxides.

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N. Hollmann, Z. Hu, Hua Wu, M. Valldor, N. Qureshi, T. Willers, Y. -Y. Chin, J. C. Cezar, A. Tanaka, N. B. Brookes, L. H. Tjeng. 2010-11-22. Orbital occupation and magnetic moments of tetrahedrally coordinated iron in CaBaFe4O7. https://doi.org/10.1103/physrevb.83.180405

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