Superfluid density in heavy fermion superconductor Ce$_{1-x}$Yb$_x$CoIn$_5$

ORAL

Abstract

Recent x-ray diffraction, electrical resistivity, magnetic susceptibility, and specific heat measurements on the superconducting heavy fermion system Ce$_{1-x}$Yb$_x$CoIn$_5$ reveal that the correlated electron state is stabilized throughout the range $0 < x < 0.8$, apparently due to cooperative behavior of Ce and Yb ions involving their unstable valences. Phase separation occurs for $x > 0.8$. Interestingly, the superconducting critical temperature decreases linearly with $x$ from 2.3 K at $x = 0$ towards 0 K at $x = 1$. Transverse-field muon spin rotation experiments have been performed on Ce$_{1-x}$Yb$_x$CoIn$_5$ alloys. Based on these measurements, we report the absolute value of magnetic penetration depth as a function of $x$ and discuss whether $T_c$ is controlled by the superfluid density of superconducting carriers. The results are compared to a recently proposed theory for the superconductivity in Ce$_{1-x}$Yb$_x$CoIn$_5$

*This work was supported by Chinese NSF, grant 11204041, NSF of Shanghai, grant 12ZR1401200, the U.S. NSF, grants DMR-0801407 (Riverside), DMR-1105380 (Los Angeles), and the U.S. DOE, contract DE-FG-02-04ER46105 (San Diego).

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Authors

  • L. Shu

    • Fudan University, China
    • University of California, San Diego

  • D.E. MacLaughlin

    • University of California, Riverside, USA

  • O.O. Bernal

    • California State University, Los Angeles, USA

  • X.P. Shen

    • Fudan University, China

  • S. Pham

    • California State University, Los Angeles, USA

  • I. Lum

    • University of California, San Diego, USA

  • M.B. Maple

    • University of California, San Diego, USA