Strain-induced orbital energy shift in antiferromagnetic RuO2 revealed by resonant elastic x-ray scattering

Abstract

In its ground state, RuO2 was long thought to be an ordinary metallic paramagnet. Recent neutron and x-ray diffraction revealed that bulk RuO2 is an antiferromagnet (AFM) with TN above 300 K. Furthermore, epitaxial strain induces novel superconductivity in thin films of RuO2 below 2 K. Here, we present a resonant elastic x-ray scattering (REXS) study at the Ru L2 edge of the strained RuO2 films exhibiting the strain-induced superconductivity. We observe an azimuthal modulation of the 100 Bragg peak consistent with canted AFM found in bulk. Most notably, in the strained films displaying novel superconductivity, we observe a ~1 eV shift of the Ru eg orbitals to a higher energy. The energy shift is smaller in thicker, relaxed films and films with a different strain direction. Our results provide further evidence of the utility of epitaxial strain as a tuning parameter in complex oxides.

20 pages, 3 main figures, 3 supplementary figures

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Cited by in corpus (5)

• Fermi-liquid behavior of non-altermagnetic RuO${}_2$
• Constraints on magnetism and correlations in RuO${}_2$ from lattice dynamics and Mössbauer spectroscopy
• Exploration of Altermagnetism in $\mathrm{Ru}{\mathrm{O}}_2$
• Surface-Localized Magnetic Order in RuO2 Thin Films Revealed by Low-Energy Muon Probes
• Ferromagnetic interface engineering of spin-charge conversion in RuO${}_2$