The Hidden Magnetism of Osmium Oxide Unveiled
The study of spin-orbit-coupled Mott insulators has unveiled surprising electronic and magnetic phenomena in 5d transition metal compounds. One such material, the double perovskite Ba₂NaOsO₆, has long been considered nonmagnetic due to the expected cancellation of its spin and orbital angular momenta. However, new insights from a combination of resonant inelastic X-ray scattering (RIXS), X-ray absorption spectroscopy (XAS), and magnetic circular dichroism (XMCD) have revealed a different scenario.
In a collaborative effort involving researchers from Diamond Light Source, ESRF, DESY, and multiple academic institutions, our team has demonstrated that strong spin-orbit coupling, covalency, and Jahn-Teller distortions collectively contribute to an unexpected finite magnetic moment in this system. This study provides direct experimental evidence of Jahn-Teller distortions at room temperature in the form of the so-called dynamic Jahn-Teller effect suggesting in Ba₂NaOsO₆, which makes its observation via conventional techniques elusive.
Our findings challenge the previous assumptions about the electronic structure of 5d¹ systems and highlight the intricate interplay of spin, orbital, and lattice degrees of freedom. The results open new perspectives for understanding magnetism in spin-orbit-coupled Mott insulators and for the magnetism of double perovskites with nominal d1 electronic configuration.
Read the full paper in Physical Review Letters: DOI: 10.1103/PhysRevLett.133.066501.
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