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Enhanced superconducting pairing interaction in indium-doped tin telluride

A. S. Erickson, J.-H. Chu, M. F. Toney, T. H. Geballe, and I. R. Fisher
Phys. Rev. B 79, 024520 – Published 30 January 2009

Abstract

The ferroelectric degenerate semiconductor Sn1δTe exhibits superconductivity with critical temperatures, Tc, of up to 0.3 K for hole densities of order 1021cm3. When doped on the tin site with greater than xc=1.7(3)% indium atoms, however, superconductivity is observed up to 2 K, though the carrier density does not change significantly. We present specific-heat data showing that a stronger pairing interaction is present for x>xc than for x<xc. By examining the effect of In dopant atoms on both Tc and the temperature of the ferroelectric structural phase transition, TSPT, we show that phonon modes related to this transition are not responsible for this Tc enhancement, and discuss a plausible candidate based on negative U pairing associated with mixed valency on the indium impurity sites.

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  • Received 15 August 2008

DOI:https://doi.org/10.1103/PhysRevB.79.024520

©2009 American Physical Society

Authors & Affiliations

A. S. Erickson1, J.-H. Chu1, M. F. Toney2, T. H. Geballe1, and I. R. Fisher1

  • 1Department of Applied Physics and Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
  • 2Stanford Synchrotron Radiation Laboratory, Menlo Park, California 94025, USA

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Issue

Vol. 79, Iss. 2 — 1 January 2009

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