Lower critical fields of superconducting PrFeAsO1y single crystals

R. Okazaki, M. Konczykowski, C. J. van der Beek, T. Kato, K. Hashimoto, M. Shimozawa, H. Shishido, M. Yamashita, M. Ishikado, H. Kito, A. Iyo, H. Eisaki, S. Shamoto, T. Shibauchi, and Y. Matsuda
Phys. Rev. B 79, 064520 – Published 19 February 2009

Abstract

We have studied the lower critical fields Hc1 of superconducting iron oxipnictide PrFeAsO1y single crystals for H parallel and perpendicular to the ab planes. Measurements of the local magnetic induction at positions straddling the sample edge by using a miniature Hall-sensor array clearly resolve the first flux penetration from the Meissner state. The temperature dependence of Hc1 for Hc is well scaled by the in-plane penetration depth without showing any unusual behavior, in contrast to previous reports. The anisotropy of penetration lengths at low temperatures is estimated to be 2.5, which is considerably smaller than the anisotropy of the coherence lengths. This is indicative of multiband superconductivity in this system in which the active band for superconductivity is more anisotropic. We also point out that the local induction measured at a position near the center of the crystal, which has been used in a number of reports for the determination of Hc1, might seriously overestimate the obtained Hc1 value.

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  • Received 22 November 2008

DOI:https://doi.org/10.1103/PhysRevB.79.064520

©2009 American Physical Society

Authors & Affiliations

R. Okazaki1, M. Konczykowski2, C. J. van der Beek2, T. Kato1, K. Hashimoto1, M. Shimozawa1, H. Shishido1, M. Yamashita1, M. Ishikado3, H. Kito4,5, A. Iyo4,5, H. Eisaki4,5, S. Shamoto3,5, T. Shibauchi1, and Y. Matsuda1,2

  • 1Department of Physics, Kyoto University, Kyoto 606-8502, Japan
  • 2Laboratorie des Solides Irradiés, CNRS-UMR 7642 & CEA/DSM/IRAMIS, Ecole Polytechnique, 91128 Palaiseau, France
  • 3Quantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai, Naka, Ibaraki 319-1195, Japan
  • 4Nanoelectronics Research Institute (NeRI), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Central 2, Umezono, Tsukuba, Ibaraki 305-8568, Japan
  • 5JST, TRIP, Chiyoda, Tokyo 102-0075, Japan

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Issue

Vol. 79, Iss. 6 — 1 February 2009

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