Anomalous Upper Critical Field in CeCoIn5/YbCoIn5 Superlattices with a Rashba-Type Heavy Fermion Interface

S. K. Goh, Y. Mizukami, H. Shishido, D. Watanabe, S. Yasumoto, M. Shimozawa, M. Yamashita, T. Terashima, Y. Yanase, T. Shibauchi, A. I. Buzdin, and Y. Matsuda
Phys. Rev. Lett. 109, 157006 – Published 12 October 2012

Abstract

We report a highly unusual angular variation of the upper critical field (Hc2) in epitaxial superlattices CeCoIn5(n)/YbCoIn5(5), formed by alternating layers of n and a 5 unit-cell thick heavy-fermion superconductor CeCoIn5 with a strong Pauli effect and normal metal YbCoIn5, respectively. For the n=3 superlattice, Hc2(θ) changes smoothly as a function of the field angle θ. However, close to the superconducting transition temperature, Hc2(θ) exhibits a cusp near the parallel field (θ=0°). This cusp behavior disappears for n=4 and 5 superlattices. This sudden disappearance suggests the relative dominance of the orbital depairing effect in the n=3 superlattice, which may be due to the suppression of the Pauli effect in a system with local inversion symmetry breaking. Taking into account the temperature dependence of Hc2(θ) as well, our results suggest that some exotic superconducting states, including a helical superconducting state, might be realized at high magnetic fields.

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  • Received 20 July 2012

DOI:https://doi.org/10.1103/PhysRevLett.109.157006

© 2012 American Physical Society

Authors & Affiliations

S. K. Goh1,2, Y. Mizukami1, H. Shishido1,*, D. Watanabe1, S. Yasumoto1, M. Shimozawa1, M. Yamashita1,†, T. Terashima3, Y. Yanase4, T. Shibauchi1, A. I. Buzdin5, and Y. Matsuda1

  • 1Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
  • 2Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
  • 3Research Center for Low Temperature and Materials Science, Kyoto University, Kyoto 606-8501, Japan
  • 4Department of Physics, Niigata University, Niigata 950-2181, Japan
  • 5Université Bordeaux I, LOMA, UMR 5798, F-33400 Talence, France

  • *Present address: Department of Physics and Electronics, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan.
  • Present address: RIKEN, Wako-shi, Saitama 351-0198, Japan.

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Issue

Vol. 109, Iss. 15 — 12 October 2012

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