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TT: Tiefe Temperaturen

TT 25: Correlated Electrons - Poster Session

TT 25.112: Poster

Mittwoch, 29. März 2006, 14:30–18:30, P1

Charge order induced pseudo gap and phonon anomalies in the superconducting cobaltate Na_xCoO₂ yH₂O — •P. Lemmens^1,2, K.-Y. Choi³, V. Gnezdilov⁴, F.C. Chou⁵, C.T. Lin¹, and B. Keimer¹ — ¹MPI-FKF, D-70569 Stuttgart, Germany — ²IPKM, TU Braunschweig, D-38106 Braunschweig — ³IMR, Tohoku Univ., Sendai — ⁴B.I. Verkin Inst. for Low Temp. Phys., NASU, 61164 Kharkov — ⁵CMSE, MIT, Cambridge, MA 02139

We report on the observation of an electronic Raman scattering continuum in nonsuperconducting and superconducting cobaltates Na_xCoO₂ yH₂O. Pronounced phonon anomalies are observed in the proximity of the metal-insulator transition and the charge ordering instabilities in Na_0.5CoO₂. We analyze the scattering rates as function of composition and emphasis an anomalous non-Fermi liquid like regime for x ≥0.5. Work supported by DFG SPP1073, ESF-HFM and MRSEC Program of NSF under award number DMR 02-13282.