Origin of Magnetism in a Supposedly Nonmagnetic Osmium Oxide
Stefano Agrestini, F. Borgatti, Piero Florio, Jonathan Frassineti, Dario Fiore Mosca, Quentin Faure, Blanka Detlefs, Christoph J. Sahle, Sonia Francoual, Jaewon Choi, Mirian García‐Fernández, Ke‐Jin Zhou, V. F. Mitrović, Patrick M. Woodward, G. Ghiringhelli, Cesare Franchini, F. Boscherini, S. Sanna, M. Moretti Sala
Abstract
A supposedly nonmagnetic 5d^{1} double perovskite oxide is investigated by a combination of spectroscopic and theoretical methods, namely, resonant inelastic x-ray scattering, x-ray absorption spectroscopy, magnetic circular dichroism, and multiplet ligand-field calculations. We found that the large spin-orbit coupling admixes the 5d t_{2g} and e_{g} orbitals, covalency raises the 5d population well above the nominal value, and the local symmetry is lower than O_{h}. The obtained electronic interactions account for the finite magnetic moment of Os in this compound and, in general, of 5d^{1} ions. Our results provide direct evidence of elusive Jahn-Teller distortions, hinting at a strong electron-lattice coupling.