Berlin 2012 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 38: Correlated Electrons: Spin Systems and Itinerant Magnets 1

TT 38.4: Talk

Thursday, March 29, 2012, 10:15–10:30, H 3010

Orbital and magnetic excitations in the weakly coupled spin chain system CaCu₂O₃ — •Valentina Bisogni¹, Krzysztof Wohlfeld¹, Roberto Kraus¹, Jan Trinckauf¹, Claude Monney², Satoshi Nishimoto¹, Ke Jin Zhou², Vladimir Strocov², Bernd Büchner¹, Jeroen van den Brink¹, Thorsten Schmitt², and Jochen Geck¹ — ¹IFW Dresden, Dresden, Germany — ²Paul Scherrer Institut, Villigen PSI, Switzerland

Recently, resonant inelastic X-ray scattering (RIXS) on the 1D spin chain system Sr₂CuO₃ has revealed an unprecedented and strong dispersion of d-d excitations. This result has been interpreted as the spin and orbital separation from the elementary electron in a 1D S=1/2 system. In this talk we report on Cu L₃ RIXS in quasi 1D CaCu₂O₃ consisting of two coupled spin chains. Due to its buckled geometry, the inter-chain interaction of this system is one order of magnitude smaller than the in-chain interaction. Therefore, CaCu₂O₃ is an ideal model system to study the effect of a weak inter-chain interaction on both the low (spin excitation) and the high (d-d excitations) energy scale. Although the dispersion of the spinon continuum can largely be accounted for by neglecting the presence of the inter-chain interaction, surprisingly the absence of a strong dispersion in the d-d excitations emerges from the raw data. A deep analysis of these results shows indeed that the various orbital channels feel different dimensionalities, 1D or 2D. The important role played by inter-chain interactions for the magnetic and orbital excitations in this class of compounds will be discussed in this context.