Raman Studies of Anisotropic Magnetic Excitations in Fluctuating Nematic Striped La2?x
Sr
x
CuO4 and the Comparison to Uniform Nd2?x
Ce
x
CuO4 |
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Authors: | S Sugai Y Takayanagi N Hayamizu Y Sone N Nakagawa T Muroi |
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Affiliation: | 1. Department of Physics, Art and Science, Petroleum Institute, P.O. Box 2533, Abu Dhabi, UAE 2. Department of Physics, Faculty of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602, Japan
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Abstract: | The mechanism of the high temperature hole-doped superconductivity was investigated by Raman scattering. The Raman selection rule is unique, so that anisotropic magnetic excitations in a fluctuating spin-charge stripe can be detected as if it is static. We use different Raman selection rules for two kinds of magnetic Raman scattering processes, two-magnon scattering and high-energy electronic scattering. In order to confirm the stripe effect, the Raman spectra of striped La2?x Sr x CuO4 (LSCO) and nonstriped Nd2?x Ce x CuO4 (NCCO) were compared. The main results in LSCO are (1) magnetic excitations are presented by individual energy dispersions for the k∥ stripe and the k⊥ stripe, (2) the charge transfer is allowed only in the direction perpendicular to the stripe. The direction is the same as the Burgers vector of an edge dislocation. Hence, we assume that a charge moves together with the edge dislocation of the charge stripe. The superconducting coherence length is close to the intercharge stripe distance at x<0.2. Therefore, we propose a model that superconducting pairs are formed in the edge dislocations. The binding energy is related to the stripe formation energy. |
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