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TT: Fachverband Tiefe Temperaturen

TT 41: CE: Spin Systems and Itinerant Magnets 1

TT 41.3: Vortrag

Mittwoch, 16. März 2011, 18:45–19:00, HSZ 105

Charge dynamics in CuGeO₃: a combined RIXS and EELS study — •Valentina Bisogni¹, Claude Monney², Roberto Kraus¹, Kejin Zhou², Vladimir Strocov², Stefan-Ludwig Drechsler¹, Jeroen van den Brink¹, Thorsten Schmitt², and Jochen Geck¹ — ¹IFW, Dresden, Germany — ²Paul Scherrer Institut, Villigen PSI, Switzerland

Model compounds of the high temperature superconductors (HTCS) are considered of big interest for the understanding of superconductivity but also for their fascinating, tuneable magnetic and electronic properties. Thanks to the low dimensionality, these model systems allow for a thorough theoretical analysis enabling to achieve a good understanding of the interactions at work. CuGeO₃ is a well known realization of one-dimensional antiferromagnetic S=1/2 spin chain, made of edge-sharing CuO₄- plaquettes, and undergoing a Spin-Peierls transition at T ≈14 K. Recently, thanks to the improved energy resolution, soft x-ray resonant inelastic scattering (RIXS) has demonstrated to be a suitable tool for the study of the HTCS. We performed RIXS experiments on CuGeO₃ at the ADRESS beamline of the Swiss Light Source. dd-excitations can be clearly observed at the Cu-L edge, while Cu-O charge transfer processes are enhanced at the O-K edge. Temperature and momentum dependent studies unambiguously identify the Zhang-Rice singlet in CuGeO₃, showing the importance of the magnetic configuration at the ground state and the Cu-O-Cu bond geometry. Complementary data measured with high resolution electron energy loss spectroscopy (EELS) are discussed in comparison with RIXS.