Resolving the orbital character of low-energy excitations in Mott insulator with intermediate spin-orbit coupling
Journal article, 2025
Multi-band Mott insulators with moderate spin-orbit and Hund’s coupling are key reference points for theoretical concept developments of correlated electron systems. The ruthenate Mott insulator Ca2RuO4 has therefore been intensively studied by spectroscopic probes. However, it has been challenging to resolve the fundamental excitations emerging from the hierarchy of electronic energy scales. Here we apply high resolution resonant inelastic x-ray scattering to probe deeper into the low-energy electronic excitations found in Ca2RuO4. In this fashion, we probe a series of spin-orbital excitations. By taking advantage of enhanced energy resolution, we probe a 40 meV mode through the oxygen K-edge. The polarization dependence of this low-energy excitations exposes a distinct orbital nature, originating from the interplay of spin-orbit coupling and octahedral rotations. Additionally, we discuss the role of magnetic correlations to describe the occurrence of excitations with amplitudes which are multiple of a given energy. Such direct determination of relevant electronic energy scales sharpens the target for theory developments of Mott insulators’ orbital degree of freedom.
Author
Karin von Arx
Chalmers, Physics, Materials Physics
University of Zürich
Pascal Rothenbühler
University of Zürich
Q. Wang
Chinese University of Hong Kong
University of Zürich
L. Martinelli
University of Zürich
Jaewon Choi
Diamond Light Source
M. Garcia-Fernandez
Diamond Light Source
S. Agrestini
Diamond Light Source
Ke Jin Zhou
Diamond Light Source
A. Vecchione
University of Salerno
National Research Council of Italy (CNR)
R. Fittipaldi
University of Salerno
National Research Council of Italy (CNR)
Yasmine Sassa
Chalmers, Physics, Materials Physics
Royal Institute of Technology (KTH)
M. Cuoco
University of Salerno
National Research Council of Italy (CNR)
Filomena Forte
National Research Council of Italy (CNR)
University of Salerno
J. Chang
University of Zürich
Communications Physics
23993650 (eISSN)
Vol. 8 1 210Realization of Novel Low‐Dimensional Skyrmion Systems
Swedish Research Council (VR) (2017-05078), 2019-06-01 -- 2021-12-31.
Gate Tuneable Superconducting Quantum Electronics (SuperGate)
European Commission (EC) (EC/H2020/964398), 2021-03-01 -- 2024-08-31.
Subject Categories (SSIF 2025)
Atom and Molecular Physics and Optics
Condensed Matter Physics
Areas of Advance
Materials Science
DOI
10.1038/s42005-025-02104-2
Related datasets
Dataset for publication "Resolving the Orbital Character of Low-energy Excitations in Mott Insulator with Intermediate Spin-orbit Coupling" [dataset]
URI: https://doi.org/10.5281/zenodo.11395839