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TT: Fachverband Tiefe Temperaturen

TT 33: Superconductivity, Measuring Devices, Matter at Low Temperature: Poster Session

TT 33.32: Poster

Mittwoch, 28. März 2012, 15:00–19:00, Poster B

Anisotropic magneto-transport in a Bi-2201 high-T_c superconductor — •Thorsten Jacobs¹, Sven-Olof Katterwe¹, Andreas Rydh¹, Holger Motzkau¹, Toni Helm², Mark V. Kartsovnik², Andrey Maljuk³, Erik Kampert⁴, Frederik Wolff-Fabris⁴, and Vladimir M. Krasnov¹ — ¹Department of Physics, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden — ²Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, 85748, Garching, Germany — ³Leibniz Institute for Solid State and Materials Research IFW Dresden, 01171 Dresden, Germany — ⁴Hochfeld-Magnetlabor Dresden, Helmholtz Zentrum Dresden-Rossendorf, 01328 Dresden, Germany

The single-CuO₂ plane cuprate superconductor Bi_2+xSr_2−yCuO_6+δ is characterized by a relatively low critical temperature and upper critical field. This allows for a complete suppression of superconductivity at low T and thus opens a possibility to study the normal-state properties with a low interference of thermal fluctuations.

We present magnetotransport measurements of small mesa structures (1 to 25 µm²) of Bi-2201 single crystals with a T_c of only ∼4 K. The tunneling conductance in the superconducting state exhibits gap-like characteristics that vanish at T_c or at a modest H_c2 ∼10 T. However, a profound negative c-axis magnetoresistance persists in the normal-state without saturating at fields up to H=65 T. This is likely due to a magnetic field suppression of an antiferromagnetic or spin/charge density wave order and provides evidence for a different origin of superconductivity and the pseudogap in cuprates.