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Journal of Low Temperature Physics

, Volume 171, Issue 1–2, pp 148–155 | Cite as

Low Temperature Heat Capacity of Layered Superconductors SrNi2Ge2 and SrPd2Ge2

  • T. L. Hung
  • I. A. Chen
  • C. H. Huang
  • C. Y. Lin
  • C. W. Chen
  • Y. B. You
  • S. T. Jian
  • M. C. Yang
  • Y. Y. Hsu
  • J. C. Ho
  • Y. Y. Chen
  • H. C. Ku
Article

Abstract

Low-temperature heat capacity C(T) of the weakly electron-correlated SrNi2Ge2 122-layer compound undergoes a superconducting transition with onset at 1.4 K and a bulk T c =0.75 K, where heat-capacity jump ratio ΔC(T c )/γT c =0.88–1.05. A small average superconducting energy gap E g (ave)=2.21 kT c =0.14 meV is derived for this multi-gap superconductor. Similar results for isostructural SrPd2Ge2 include T c (onset)=3.5 K, bulk T c of 2.92 K, ΔC(T c )/γT c =0.70 and E g (ave)=2.54 kT c =0.64 meV. The higher T c onset could be associated with stoichiometric 1:2:2 grains in the polycrystalline samples. In addition, deviations of E g /kT c from the BCS ratio of 3.5 suggest that, just like their iron-based counterpart, these 122-layer germanides may also exhibit an unconventional, fully-opened multi-gap s-wave superconductivity.

Keywords

Superconducting materials Heat capacity 122-layer germanide 

Notes

Acknowledgements

This work was supported by Grants No. NSC101-2112-M-007-013-009-MY3 and NSC100-2112-M-001-019-MY3 of the National Science Council of the Republic of China.

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Copyright information

© Springer Science+Business Media New York 2012

Authors and Affiliations

  • T. L. Hung
    • 1
  • I. A. Chen
    • 1
  • C. H. Huang
    • 1
  • C. Y. Lin
    • 1
  • C. W. Chen
    • 1
  • Y. B. You
    • 1
  • S. T. Jian
    • 2
  • M. C. Yang
    • 2
  • Y. Y. Hsu
    • 2
  • J. C. Ho
    • 3
  • Y. Y. Chen
    • 3
  • H. C. Ku
    • 1
  1. 1.Department of PhysicsNational Tsing Hua UniversityHsinchuTaiwan, ROC
  2. 2.Department of PhysicsNational Taiwan Normal UniversityTaipeiTaiwan, ROC
  3. 3.Institute of PhysicsAcademia SinicaTaipeiTaiwan, ROC

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