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.
Author
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
Physical Review B
2469-9950 (ISSN) 2469-9969 (eISSN)
Vol. 101 20 205117Subject Categories
Condensed Matter Physics
DOI
10.1103/PhysRevB.101.205117