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TT: Fachverband Tiefe Temperaturen

TT 12: Poster Session Superconductivity

TT 12.55: Poster

Monday, March 11, 2013, 15:00–19:00, Poster D

High-Field Magnetotransport in the Electron-Doped Cuprate Superconductor Nd_2−xCe_xCuO₄ — •Toni Helm¹, M .V. Kartsovnik¹, E. Kampert², C. Putzke², W. Biberacher¹, P. D. Grigoriev³, S. Baddoux⁴, C. Proust⁴, I. Sheikin⁴, A. Kiswandhi⁵, J. S. Brooks⁵, E. S. Choi⁵, J. Wosnitza², A. Erb¹, and R. Gross¹ — ¹Walther-Meissner-Institute, Garching, Germany — ²High Magnetic Field Laboratory, Dresden, Germany — ³L. D. Landau Institute for Theoretical Physics, Chernogolovka, Russia — ⁴Laboratoire National des Champs Magnétiques Intenses CNRS, Toulouse-Grenoble, France — ⁵National High Magnetic Field Laboratory,Tallahassee, USA

The current status of the high-field magnetotransport studies of the Fermi surface in the electron-doped cuprate superconductor Nd_2−xCe_xCuO₄ will be presented. Both the magnetic quantum oscillations and semiclassical angle-dependent magnetoresistance give evidence of a weak (π/a, π/a)-superlattice potential existing at the overdoped regime, 0.15≤ x≤ 0.17. The relevant energy gap is very small, ∼ 10−2 eV; it is gradually suppressed at increasing the doping level, extrapolating to zero right at the edge of the superconducting dome, x = 0.175. On the other hand, decreasing the doping below the optimal level leads to dramatic changes in the behavior of magnetotransport including the Shubnikov-de Haas oscillations, magnetoresistance and Hall effect. Our data suggest a Fermi surface transformation leading to a collapse of the classical closed cyclotron orbits responsible for the conventional galvanomagnetic effects.