Transport and Point Contact Measurements on Pr1−xCexPt4Ge12 Superconducting Polycrystals

Abstract

We performed a detailed investigation of the superconducting properties of polycrystalline Pr1−xCexPt4Ge12 pellets. We report the effect of Ce substitution, for x = 0.07, on magnetic field phase diagram H-T. We demonstrate that the upper critical field is well described by the Ginzburg–Landau model and that the irreversibility field line has a scaling behaviour similar to cuprates. We also show that for magnetic fields lower than 0.4 T, the activation energy follows a power law of the type ?−1/2, suggesting a collective pinning regime with a quasi-2D character for the Ce-doped compound with x = 0.07. Furthermore, by means of a point contact Andreev reflection spectroscopy setup, we formed metal/superconductor nano-junctions as small as tens of nanometers on the PrPt4Ge12 parent compound (x = 0). Experimental results showed a wide variety of conductance features appearing in the dI/dV vs. V spectra, all explained in terms of a modified Blonder–Tinkham–Klapwijk model considering a superconducting order parameter with nodal directions as well as sign change in the momentum space for the sample with x = 0. The numerical simulations of the conductance spectra also demonstrate that s-wave pairing and anisotropic s-waves are unsuitable for reproducing experimental data obtained at low temperature on the un-doped compound. Interestingly, we show that the polycrystalline nature of the superconducting PrPt4Ge12 sample can favour the formation of an inter-grain Josephson junction in series with the point contact junction in this kind of experiments.

Superior tunable photocatalytic properties for water splitting in two dimensional GeC/SiC van der Waals heterobilayers

“…For instance, C 3 N 4 (g-C 3 N 4 ), a graphene-like metal-free 2D photocatalyst, can produce ~ 3.2 μmol/h/g of H 2 when larger than 420 nm wavelength photons impinge upon it. The surface area of g-C 3 N 4 is ~ 10 m 2 /g, and it exhibits a bandgap of ~ 2.7 eV in the ultra-violet (UV) region 11 . The amount of H 2 yield (~ 3700 μmol/h/g) from the g-C 3 N 4 is ~ 35 times higher than that obtained with Pt co-catalysts 12 .…”

“…Due to the characteristics of high bandgap tunability, controllable interlayer spacing, unique in-plane and interfacial thermal transport, formation of type I–II bandgap, and efficient spatial carrier separations, vdW hetero-bilayers capture the core concentration of photocatalytic operation 17 – 26 . In recent years, several studies focused on the advancement of photocatalytic water-splitting by forming and considering broad bandgap vdWHs 11 , 27 – 30 .…”

Gate-Tunable Negative Differential Conductance in Hybrid Semiconductor–Superconductor Devices

“…On the other hand, for the measurement of pointcontact spectroscopy, the positive differential conductance dip has been extensively reported [44][45][46][47][48][49][50] and can be generally attributed to the critical supercurrent effect due to the Maxwell resistance in the non-ballistic regime, as reported by Sheet et al [45] Moreover, Shan et al [44] explained the dip using the combination of superconducting proximity in the normal metal and Josephson tunnelling in the polycrystalline superconductor.…”