Regensburg 2010 – wissenschaftliches Programm
TT 24.6: Hauptvortrag
Mittwoch, 24. März 2010, 15:30–16:00, H19
Fermi Surface Evolution in an Electron-Doped Cuprate Superconductor Revealed by High-Field Magnetotransport — •Mark Kartsovnik — Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Garching, Germany
Establishing the Fermi surface topology and its dependence on carrier concentration is fundamentally important for understanding the role of electronic correlations and resulting ordering instabilities in superconducting paring in high-Tc cuprates. I will present recent experiments on magnetic quantum oscillations in the electron-doped cuprate Nd2−xCexCuO4 providing direct evidence for a well-defined continuous Fermi surface and its evolution with doping level. Most interestingly, the Fermi surface is found to be reconstructed, most likely due to a magnetic ordering which occurs at a critical doping level significantly exceeding the optimal doping. Besides quantum oscillations, we have found semiclassical angle-dependent magnetoresistance oscillations (AMRO) which are directly related to the geometry of the underlying Fermi surface. The analysis of the AMRO in combination with the Shubnikov-de Haas data shows that a superlattice potential survives over the entire superconducting doping range. This suggests an intimate relation between magnetic ordering and superconductivity.
The work was done in cooperation with T. Helm, W. Biberacher, M. Bartkowiak, I. Sheikin, M. Lambacher, A. Erb, N. Bittner, J. Wosnitza, and R. Gross and supported by the DFG via Research Unit 538 and EuroMagNET II.