B2: Photon scattering from spin-orbit materials
Eva Benckiser, Matthias Hepting, Bernhard Keimer
In the presence of strong spin-orbit coupling, correlated-electron materials display a rich set of emergent phenomena, such as proximate spin liquid phases. We will use Raman scattering and resonant inelastic x-ray scattering (RIXS) to elucidate the microscopic origin of these phenomena in several 4d and 5d electron materialswith frustrated exchange interactions. Furthermore, we will explore soft-chemistry topotactic modifications of the structural and electronic properties of these materials.
Publications
2024 |
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Wang, L.; Liu, H.; Zimmermann, V.; Yogi, A. K.; Isobe, M.; Minola, M.; Hepting, M.; Khaliullin, G.; Keimer, B. Spin-Orbit Excitons in a Correlated Metal: Raman Scattering Study of Sr2RhO4 Journal Article Phys. Rev. Lett. 132, 116502, 2024. @article{wang_spin-orbit_2024, Using Raman spectroscopy to study the correlated 4d-electron metal Sr2RhO4, we observe pronounced excitations at 220 meV and 240 meV with A1g and B1g symmetries, respectively. We identify them as transitions between the spin-orbit multiplets of the Rh ions, in close analogy to the spin-orbit excitons in the Mott insulators Sr2IrO4 and α−RuCl3. This observation provides direct evidence for the unquenched spin-orbit coupling in Sr2RhO4. A quantitative analysis of the data reveals that the tetragonal crystal field Δ in Sr2RhO4 has a sign opposite to that in insulating Sr2IrO4, which enhances the planar xy orbital character of the effective J=1/2 wave function. This supports a metallic ground state, and suggests that c-axis compression of Sr2RhO4 may transform it into a quasi-two-dimensional antiferromagnetic insulator. |