Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 12: Correlated Electrons: Spin Systems and Itinerant Magnets 2
TT 12.7: Vortrag
Montag, 23. März 2009, 15:45–16:00, HSZ 304
Orbitons and bi-orbitons in YVO3 — •Luis Mäder1, Eva Benckiser1,2, Giacomo Ghiringhelli3, Marco Moretti3, Graeme R. Blake4, Nandang Mufti4, A. Agung Nugroho4,5, Thomas T. M. Palstra4, Maurits Haverkort2, and Markus Grüninger1 — 1Universität zu Köln — 2MPI-FKF Stuttgart — 3Politecnico di Milano — 4University of Groningen — 5Institut Teknologi Bandung
The aim of the project is the unambiguous observation of a novel kind of elementary excitations in a solid, namely orbitons, propagating orbital excitations. In an orbitally ordered state, one expects that exchange interactions between orbitals on neighbouring sites give rise to a significant dispersion of the orbital excitations. These orbitons are analogous to spin waves in a magnetically ordered state.
Orbital exchange interactions are expected to be strong in the Mott insulator YVO3.
Here, we report on the observation of orbital excitations in YVO3 by means of high-resolution resonant inelastic x-ray scattering (RIXS) across the V L3,2 (V 2p → V 3d) and O K (O 1s → O 2p) edges with the new SAXES beamline at the PSI, Villigen. Due to the excellent resolution of 60-70 meV, we are able to resolve the intra-t2g excitations, spin-flip excitations within the t2g shell, and excitations into the eg levels, in excellent agreement with our recent optical data [1]. Moreover, we find evidence for a bi-orbiton excitation. Finally, our data show that SAXES in principle should allow to study the orbital excitations as a function of the wave vector k.
[1] E. Benckiser et al., New J. Phys. 10, 053027 (2008).