Spurious second transition in the heavy-fermion superconductor CePt3Si

Abstract

Specific heat studies have shown a distinct second transition at T≈0.48K in some nominally single-phase samples of the heavy Fermion superconductor CePt3Si, Tc=0.75K, which in the current work is also seen as structure in penetration depth measurements. The double transition structure is accentuated by a Ce deficiency in Ce1−xPt3Si, becoming reproducible for x⩾2%. Electron microprobe, x-ray diffraction, and metallography studies of these Ce-deficient samples show only a minor amount of second phase which, by secondary electron backscattering, is similar in composition to Ce2Pt15Si7. This compound is an antiferromagnet with a peak in C∕T at 0.4K with a magnitude of 22000mJ(Ce−molK2)−1. Thus, in the complexity of a the Ce−Pt−Si ternary phase diagram, the cause for the occasionally observed structure in the specific heat below the superconducting transition is a few tenths of a percent mass loss of Ce during arc-melting or annealing of the sample.

Source-reported materials — not catalogue approval

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