T. Takayama, K. Kuwano, D. Hirai, Y. Katsura, A. Yamamoto, H. Takagi
We report the discovery of a family of ternary platinum phosphides APt3P (A = Ca, Sr and La), which crystallize in an antiperovskite-based structure closely related to that of the heavy fermion superconductor CePt3Si. All three phosphides showed superconductivity at low temperatures and the highest critical temperature Tc = 8.4 K was observed for SrPt3P. The analysis of specific heat C(T) for SrPt3P shows clear evidence for very strong coupling s-wave superconductivity with a large ratio between superconducting gap D0 and Tc, 2D0/kBTc ~ 5, and the presence of low-energy phonons. The presence of multiple Fermi surface pockets was inferred from the nonlinear magnetic field dependence of Hall resistivity, which we argue might play a role in realizing the strong coupling of charge carriers with the low lying phonons.
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http://arxiv.org/abs/1205.1589
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