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Spin-Orbital Excitations in Ca2RuO4 Revealed by Resonant Inelastic X-Ray Scattering

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Das L., Forte F., Fittipaldi R., Fatuzzo C. G., Granata V., Ivashko O., Horio M., Schindler F., Dantz M., Tseng Yi, McNally D. E., Rønnow H. M., Wan W., Christensen N. B., Pelliciari J., Olalde-Velasco P., Kikugawa N., Neupert T., Vecchione A., Schmitt T., Cuoco M., Chang J.,
Project Coupled spin, charge and orbital dynamics of low-dimensional cuprates
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Original article (peer-reviewed)

Journal Physical Review X
Volume (Issue) 8(1)
Page(s) 011048 - 011048
Title of proceedings Physical Review X
DOI 10.1103/physrevx.8.011048

Open Access

URL http://doi.org/10.1103/PhysRevX.8.011048
Type of Open Access Publisher (Gold Open Access)

Abstract

The strongly correlated insulator Ca2RuO4 is considered as a paradigmatic realization of both spin-orbital physics and a band-Mott insulating phase, characterized by orbitally selective coexistence of a band and a Mott gap. We present a high resolution oxygen K-edge resonant inelastic x-ray scattering study of the antiferromagnetic Mott insulating state of Ca2RuO4. A set of low-energy (about 80 and 400 meV) and high-energy (about 1.3 and 2.2 eV) excitations are reported, which show strong incident light polarization dependence. Our results strongly support a spin-orbit coupled band-Mott scenario and explore in detail the nature of its exotic excitations. Guided by theoretical modeling, we interpret the low-energy excitations as a result of composite spin-orbital excitations. Their nature unveils the intricate interplay of crystal-field splitting and spin-orbit coupling in the band-Mott scenario. The high-energy excitations correspond to intra-atomic singlet-triplet transitions at an energy scale set by Hund’s coupling. Our findings give a unifying picture of the spin and orbital excitations in the band-Mott insulator Ca2RuO4.
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