Probing the unconventional superconductivity of PrPt$_4$Ge$_{12}$ through Ce substitution

ORAL

Abstract

Superconductivity has been observed in a new class of filled skutterudite compounds of the form $M$Pt$_{4}$Ge$_{12}$ ($M$ = Sr, Ba, La, Pr, and Th), with the Pr member exhibiting a high superconducting transition temperature $T_c$ $\sim$ 7.9 K. Most of these skutterudite compounds seems to exhibit conventional BCS-type superconductivity; however, superconductivity in Pr appears to be unconventional as it exhibits characteristics of time-reversal symmetry breaking. To help clarify the nature of the superconductivity in PrPt$_4$Ge$_{12}$, we studied the response of superconductivity to the substitution of Ce for Pr throughout the series Pr$_{1-x}$Ce$_x$Pt$_4$Ge$_{12}$ (0 $\leq$ x $\leq$ 1). Measurements of electrical resistivity, magnetic susceptibility, and specific heat were performed and superconductivity were observed up to a Ce concentration of 50$\%$. A pronounced change was observed in the temperature dependence of specific heat below $T_c$ where PrPt$_4$Ge$_{12}$ exhibits a crossover from a $T^3$ to an exponential temperature dependence when Ce is introduced.

*Research supported by US AFOSR under MURI grant NO. FA 9550-09-1-0603, US NSF under grant NO. DMR 0802478, and US DoE under grant NO. FG0204-ER46105 and grant NO. FG02-04-ER46178.

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Authors

  • Kevin Huang

    • Department of Physics, University of California, San Diego, La Jolla, California 92093

  • Lei Shu

    • Department of Physics, University of California, San Diego, La Jolla, California 92093

  • I. Lum

    • Department of Physics, University of California, San Diego, La Jolla, California 92093
    • University of California, San Diego

  • B.D. White

    • University of California, San Diego
    • Department of Physics, University of California, San Diego, La Jolla, California 92093

  • Marc Janoschek

    • Department of Physics, University of California, San Diego, La Jolla, California 92093

  • Duygu Yazici

    • Department of Physics, University of California, San Diego, La Jolla, California 92093
    • University of California, San Diego

  • James J. Hamlin

    • Department of Physics, University of California, San Diego, La Jolla, California 92093

  • Diego A. Zocco

    • Department of Physics, University of California, San Diego, La Jolla, California 92093

  • Pei-Chun Ho

    • Department of Physics, California State University Fresno, Fresno, California 93740

  • Ryan E. Baumbach

    • Los Alamos National Laboratory
    • Department of Physics, University of California, San Diego, La Jolla, California 92093

  • M.B. Maple

    • UC San Diego
    • Department of Physics, University of California, San Diego, La Jolla, California 92093
    • University of California, San Diego