Regensburg 2004 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 2: Supraleitung: Mechanismen, Phasendiagramm, konkurrierende Ordnungen

TT 2.3: Vortrag

Montag, 8. März 2004, 12:00–12:15, H20

Dimensionality of magnetic excitations in untwinned YBCO - an inelastic neutron scattering study — •Vladimir Hinkov¹, Bernhard Keimer¹, Pailhes Stephane², Bourges Philippe², Sidis Yvan², Lin CT¹, and Kulakov Andrej¹ — ¹MPI für Festkörperforschung, Stuttgart, Germany — ²Laboratoire Leon Brillouin, Saclay, France

Theories trying to describe superconductivity in the high-Tc cuprates are based on 2D-scenarios of strongly correlated charge carriers. The CuO2-planes in the LSCO family are unstable against the formation of 1D "stripesNo-dq of antiferromagnetically ordered Cu spins separated by periodically spaced hole domain walls which should result in an 1D response in inelastic neutron scattering (INS). It is of great significance for theory, if stripe phases are common for all high-Tc cuprates. Investigation in YBCO is complicated by twinning - the fact that equal proportions of twin domains with mutually perpendicular directions of the a*- and b*-axes exist in the crystal. This automatically leads to a overall 2D response, even if the separate domains show a 1D response. We present the world-wide first INS-study of fully twin-free optimally doped YBCO and demonstrate that the response is still 2D, although a strong anisotropy between the a*- and b*-axes exist. We give a precise mapping of the relevant (E,q) space allowing to discriminate between different theories.