E. Benckiser, L. Fels, G. Ghiringhelli, M. Moretti Sala, T. Schmitt, J. Schlappa, V.N. Strocov, N. Mufti, G.R. Blake, A.A. Nugroho, T.T.M. Palstra, M.W. Haverkort, K. Wohlfeld, M. Grüninger
We report on the observation of orbital excitations in YVO3 by means of resonant inelastic x-ray scattering (RIXS) at energies across the vanadium L3 and oxygen K absorption edges. At the V L3 edge, we are able to resolve the full spectrum of orbital excitations up to 5 eV. In order to unravel the effect of superexchange interactions and the crystal field on the orbital excitations, we analyzed the energy and temperature dependence of the intra-t2g excitations at 0.1-0.2 eV in detail. While these results suggest a dominant influence of the crystal field, peak shifts of about 13-20 meV observed as a function of the transferred momentum qa reflect a finite dispersion of the orbital excitations. This is puzzling since theoretical models based on superexchange interactions predict a dispersion only for qc. Furthermore, we demonstrate that RIXS at the O K edge is very sensitive to intersite excitations. At the O K edge, we observe excitations across the Mott-Hubbard gap and an additional feature at 0.4 eV, which we attribute to two-orbiton scattering, i.e., an exchange of orbitals between adjacent sites. Altogether, our results indicate that both superexchange interactions and the crystal field are important for a quantitative understanding of the orbital excitations in YVO3. © 2013 American Physical Society.
II. Physikalisches Institut, Universität zu Köln, 50937 Köln, Zülpicher Str. 77, Germany; Max Planck Institute for Solid State Research, 70569 Stuttgart, Heisenbergstraße 1, Germany; CNR/SPIN, Dipartimento di Fisica, Politecnico di Milano, 20133 Milano, piazza Leonardo da Vinci 32, Italy; European Synchrotron Radiation Facility, 38043 Grenoble Cedex, BP 220, France; Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland; Institut Methoden und Instrumentierung der Synchrotronstrahlung, BESSY II, 12489 Berlin, Albert-Einstein-Str. 15, Germany; Department of Chemical Physics, Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, Nijenborgh 4, Netherlands; Department of Physics, State University of Malang, 65145 Malang, Jl. Semarang No. 5, Indonesia; Jurusan Fisika, Institut Teknologi Bandung, Bandung 40132, Jl. Ganesha 10, Indonesia; Department of Physics and Astronomy, University of British Columbia, Vancouver V6T 1Z1, Canada; Institute for Theoretical Solid State Physics, IFW Dresden, D-01069 Dresden, Germany; Stanford Institute for Materials and Energy Sciences, Stanford University, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, United States
