Evolution of ground state and upper critical field in R$_{1-x}$Gd$_x$Ni$_2$B$_2$C (R = Lu, Y): Coexistence of superconductivity and spin-glass state

ORAL

Abstract

We report effects of local magnetic moment, Gd$^{3+}$, doping ($x \leq 0.3$) on superconducting and magnetic properties of the closely related Lu$_{1-x}$Gd$_x$Ni$_2$B$_2$C and Y$_{1- x}$Gd$_x$Ni$_2$B$_2$C series. The superconducting transition temperature decreases and the heat capacity jump associated with it drops rapidly with Gd-doping; qualitative changes with doping are also observed in the temperature-dependent upper critical field behavior, and a region of coexistence of superconductivity and spin-glass state is delineated on the $x - T$ phase diagram. The evolution of superconducting properties can be understood within the Abrikosov-Gor'kov theory of magnetic impurities in superconductors taking into account the paramagnetic effect on upper critical field and the details of the $x - T$ phase diagrams.

*Supported by the US DOE - BES under Contract No. DE-AC02-07CH11358.

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Authors

  • Sergey Bud'ko

    • Ames Laboratory
    • Ames Laboratory U.S. DOE and Department of Physics and Astronomy, Iowa State University
    • Iowa State University
    • Iowa State University and Ames Lab.
    • Iowa State University/Ames Lab
    • Iowa State University and Ames Laboratory US DOE
    • Ames Laboratory and Iowa State University, IA, USA
    • Ames Laboratory, Iowa State University

  • V.G. Kogan

  • H. Hodovanets

  • S. Ran

  • S.A. Moser

  • M.J. Lampe

  • Paul Canfield

    • Ames Laboratory and Dept. of Physics and Astronomy, Iowa State University
    • Ames Laboratory U.S. DOE and Department of Physics and Astronomy, Iowa State University
    • Iowa State University
    • Iowa State University and Ames Lab.
    • Iowa State University/Ames Lab
    • Iowa State University, Ames Laboratory
    • Ames Laboratory and Iowa State University, IA, USA
    • Ames Laboratory, Ames, IA 50011, U.S.A.
    • Ames Laboratory, Iowa State University