Dresden 2009 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 12: Correlated Electrons: Spin Systems and Itinerant Magnets 2

TT 12.6: Vortrag

Montag, 23. März 2009, 15:30–15:45, HSZ 304

Collective spin-excitations in Cu L and O K edge Resonant Inelastic X-ray Scattering from Sr₁₄Cu₂₄O₄₁ — •Thorsten Schmitt¹, Justina Schlappa¹, F. Vernay¹, V. Strocov¹, V. Ilakovac², B. Thielemann¹, H. Ronnow¹, J. Mesot¹, B. Delley¹, and L. Patthey¹ — ¹Paul Scherrer Institut, Villigen PSI, Switzerland — ²UPMC, Paris, France

The spin-ladder / spin-chain compound Sr₁₄Cu₂₄O₄₁ is a low-dimensional spin system, which is known for its complex interplay between charge and spin degrees of freedom. One of the subsystems is formed by 2-leg ladders Cu₂O₃, which have the properties of a spin liquid with a finite spin gap [1]. Resonant inelastic X-ray scattering (RIXS) is a powerful probe of the electronic ground state and the low-energy excitation spectrum of transition-metal oxides, being directly sensitive to the valence electron configuration [2]. Using RIXS at the Cu L₃ and O K edge of Sr₁₄Cu₂₄O₄₁ [1,2] we observe collective spin-excitations from the ladders, which we assign to two-triplon modes [3]. At the Cu L₃ resonance the dispersion of the modes was mapped out depending on the momentum transfer with excellent sensitivity over almost the entire first Brillouin-zone, in contrast to inelastic neutron scattering [4]. Site-sensitive RIXS at the O K edge of the chain- and ladder-subsystems give insight into the character of the holes.

[1] T. Vuletic et al., Physics Reports 428, 169-258 (2006).

[2] A. Kotani and S. Shin, Rev. Mod. Phys. 73, 203 (2001).

[3] K. P. Schmidt and G. S Uhrig. Mod. Phys. Rev. Lett. 90, 227204 (2003).

[4] S. Notbohm et al., Phys. Rev. Lett. 98, 027403 (2007).