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Point-contact spectroscopy in heavy-fermion superconductors

Mikael Fogelström, W. K. Park, L. H. Greene, G. Goll, and Matthias J. Graf
Phys. Rev. B 82, 014527 – Published 20 July 2010

Abstract

We develop a microscopic model to calculate point-contact spectra between a metallic tip and a superconducting heavy-fermion system. We apply our tunneling model to the heavy fermion CeCoIn5, both in the normal and superconducting states. In point contact and scanning tunneling spectroscopy many heavy-fermion materials, such as CeCoIn5, exhibit an asymmetric differential conductance, dI/dV, combined with a strongly suppressed Andreev reflection signal in the superconducting state. We argue that both features may be explained in terms of a multichannel tunneling model in the presence of localized states near the interface. We find that it is not sufficient to tunnel into two itinerant bands of light and heavy electrons to explain the Fano line shape of the differential conductance. Localized states in the bulk or near the interface are an essential component for quantum interference to occur when an electron tunnels from the metallic tip of the point contact into the heavy-fermion system.

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  • Received 4 May 2010

DOI:https://doi.org/10.1103/PhysRevB.82.014527

©2010 American Physical Society

Authors & Affiliations

Mikael Fogelström1, W. K. Park2, L. H. Greene2, G. Goll3, and Matthias J. Graf4

  • 1Department of Microtechnology and Nanoscience, Chalmers, S-412 96 Göteborg, Sweden
  • 2Department of Physics and the Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana–Champaign, Urbana, Illinois 61801-3080, USA
  • 3DFG-Center for Functional Nanostructures, Karlsruhe Institute of Technology, D-76131 Karlsruhe, Germany
  • 4Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA

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Issue

Vol. 82, Iss. 1 — 1 July 2010

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