Berlin 2005 – scientific programme

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TT: Tiefe Temperaturen

TT 23: Posters Superconductivity, Solids at Low Temperature

TT 23.16: Poster

Monday, March 7, 2005, 14:00–18:00, Poster TU D

Raman scattering from charge ordering fluctuations in cuprates — •Leonardo Tassini¹, Francesca Venturini¹, Rudi Hackl¹, Qing-Ming Zhang², Andreas Erb¹, Naoki Kikugawa³, and Toshizo Fujita³ — ¹Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, D-85748 Garching — ²Department of Physics, Nanjing University, Nanjing 210093, P.R. China — ³ADSM, Hiroshima University, Higashi-Hiroshima 739-8526

The electronic Raman effect has been studied in differently doped single crystals of La_2−xSr_xCuO₄ (LSCO) and of Y_0.97Ca_0.03Ba₂Cu₃O₆ (YBCO). The experimental data provide direct evidence of the formation of one-dimensional charged structures in the two-dimensional CuO₂ planes. The stripes manifest themselves in a Drude-like peak at low energies and temperatures. The selection rules allow to determine the orientation to be along the principle axes at x = p = 0.10 in LSCO and along the diagonals at p = 0.02 in LSCO and YBCO. The stripes fluctuate, and the correlation length is of the order of the electronic mean free path. In LSCO the temperature is the only scale of the response at different doping levels demonstrating the importance of quantum critical behavior. We provide an estimate of the quantum critical point in LSCO at x_c = 0.18.