Mobile orbitons in Ca2CuO3: Crucial role of Hund's exchange
Artikel i vetenskaplig tidskrift, 2020

We investigate the CuL3 edge resonant inelastic x-ray scattering (RIXS) spectra of a quasi-1D antiferromagnet Ca2CuO3. In addition to the magnetic excitations, which are well-described by the two-spinon continuum, we observe two dispersive orbital excitations, the 3d(xy) and the 3d(yz) orbitons. We carry out a quantitative comparison of the RIXS spectra, obtained with two distinct incident polarizations, with a theoretical model. We show that any realistic spin-orbital model needs to include a finite, but realistic, Hund's exchange J(H) approximate to 0.5 eV. Its main effect is an increase in orbiton velocities, so that their theoretically calculated values match those observed experimentally. Even though Hund's exchange also mediates some interaction between spinon and orbiton, the picture of spin-orbit separation remains intact and describes orbiton motion in this compound.


R. Fumagalli

Politecnico di Milano

J. Heverhagen

Universität Stuttgart

D. Betto

Max-Planck Institute für Festkörperforschung

European Synchrotron Radiation Facility (ESRF)

Riccardo Arpaia

Politecnico di Milano

Chalmers, Mikroteknologi och nanovetenskap, Kvantkomponentfysik

M. Rossi

Stanford University

D. Di Castro

Universita degli Studi di Roma Tor Vergata

N. B. Brookes

European Synchrotron Radiation Facility (ESRF)

M. Moretti Sala

Politecnico di Milano

M. Daghofer

Universität Stuttgart

L. Braicovich

European Synchrotron Radiation Facility (ESRF)

Politecnico di Milano

K. Wohlfeld

Uniwersytet Warszawski

G. Ghiringhelli

Politecnico di Milano


2469-9950 (ISSN) 2469-9969 (eISSN)

Vol. 101 20 205117


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