Dresden 2006 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 27: Symposium Twenty Years High-T_c Cuprates - Recent Progress

TT 27.4: Fachvortrag

Donnerstag, 30. März 2006, 11:30–12:00, HSZ 02

Universal magnetic spectrum in high-temperature superconductors — •Bernhard Keimer — Max-Planck-Institut für Festkörperforschung, 70569 Stuttgart

We outline recent experimental evidence for a magnetic excitation spectrum of the cuprate high-temperature superconductors whose main features are independent of materials-specific details. The spectrum consists of upward- and downward-dispersing branches that merge at the wave vector characteristic of antiferromagnetism in the undoped parent compounds. We will argue that information about the in-plane anisotropy of the spectrum is crucial for its microscopic interpretation. In order to determine this anisotropy, we have use neutron scattering to collect an extensive data set on untwinned YBa₂Cu₃O_6+x single crystals with different doping levels x. The results will be compared to calculations based on Fermi-liquid states and states with static and dynamic No-dqstripeNo-dq order. Combined with complementary photoemission data on the same single samples, these data provide a detailed, microscopic picture of the interaction between spin and charge excitations in the copper oxide superconductors.

Collaborators: V. Hinkov, S. Pailhès, P. Bourges, Y. Sidis, A. Ivanov, A. Kulakov, C.T. Lin, D.P. Chen, C. Bernhard

This work is supported by the Deutsche Forschungsgemeinschaft (Research unit 538).

Recent publications: B. Keimer, Nature 430, 650 (2004); S. Pailhès, Y. Sidis, P. Bourges, V. Hinkov, A. Ivanov, C. Ulrich, L.P. Regnault, and B. Keimer, Phys. Rev. Lett. 93, 167001 (2004).