Neutron scattering study of charge fluctuations and spin fluctuations in optimally doped YBa2Cu3O6.95

• Published in: Physica. C, Superconductivity Superconductivity, 2004-10, Vol.412-414, p.70-75
• Main Authors: Pintschovius, Lothar, Endoh, Yasuo, Reznik, Dmitry, Hiraka, H., Tranquada, John, Reichardt, Winfried, Bourges, Philippe, Sidis, Yvan, Uchiyama, Hiroshi, Masui, T., Tajima, Setsuko
• Format: Article
• Language: English
• ISSN: 0921-4534
• DOI: 10.1016/j.physc.2004.01.065

Inelastic neutron scattering investigations on optimally doped YBCO revealed a very pronounced temperature dependence of the Cu-O in-plane bond-stretching vibrations along the (010)-direction: a downward shift of spectral weight with decreasing temperature by at least 10 meV in a narrow range of wave vectors halfway to the zone boundary. The temperature evolution starts around 200 K, well above the superconducting transition temperature. This phonon anomaly provides strong evidence for large electron-phonon coupling. It also indicates an incipient charge density wave instability within the CuO2 planes reminiscent of dynamical charge stripes. The magnetic fluctuations have been investigated in great detail on the same sample. Incommensurate spin fluctuations have been observed for energies both below and above the energy of the resonance peak at E=41 meV. However, the dispersive nature of these fluctuations as well as their apparent isotropy in the basal plane speak against an interpretation of the spin fluctuation spectrum in the framework of the classical stripe phase picture.