Mobile orbitons in Ca2CuO3: Crucial role of Hund's exchange
Journal article, 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

Polytechnic University of Milan

J. Heverhagen

University of Stuttgart

D. Betto

Max-Planck Institute for Solid State Research

European Synchrotron Radiation Facility (ESRF)

Riccardo Arpaia

Polytechnic University of Milan

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics

M. Rossi

Stanford University

D. Di Castro

University of Rome Tor Vergata

N. B. Brookes

European Synchrotron Radiation Facility (ESRF)

M. Moretti Sala

Polytechnic University of Milan

M. Daghofer

University of Stuttgart

L. Braicovich

European Synchrotron Radiation Facility (ESRF)

Polytechnic University of Milan

K. Wohlfeld

University of Warsaw

G. Ghiringhelli

Polytechnic University of Milan


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

Vol. 101 20 205117

Subject Categories

Condensed Matter Physics



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