Superconductivity in hole-doped germanium point contacts

Abstract

We have observed superconductivity in heavy p-doped Ge by measuring of differential resistance dV/dI(V) of Ge - PtIr point contacts. The superconducting (SC) features disappear above 6 K or above 1 T, what can be taken as the critical temperature and the critical magnetic field, respectively. The observed dV/dI(V) spectrum with Andreev reflection like features was fitted within one-gap Blonder-Tinkham-Klapwijk model. The extracted SC gap demonstrates Bardeen-Cooper-Schrieffer-like behavior with 2 Delta/kBTc = 10+/-1 ratio, which is much higher that expected for conventional superconductors. Magnetic field suppresses Andreev reflection features, but the SC gap moderately decreases in magnetic field similarly as it was observed previously for the type-II superconductors, including nickel borocarbide and iron-based superconductors. Curiously, we have not yet observed superconductivity in n-doped Ge with a similar dopant concentration.

arXiv comment8 pages, 4 figures, with Supplement: 2 pages, 3 figures

References in corpus (8)

• Unconventional Superconductivity at Mesoscopic Point-contacts on the 3-Dimensional Dirac Semi-metal Cd${}_3$As${}_2$
• Andreev Reflection Spectroscopy in Niobium Point Contacts in Magnetic Field
• Superconductivity in single-crystalline, aluminum- and gallium-hyperdoped germanium
• Point-contact spectroscopy of the antiferromagnetic superconductor HoNi2B2C in the normal and superconducting state
• Anatomy of point-contact Andreev reflection spectroscopy from the experimental point of view (review)
• The superconducting gaps in FeSe studied by soft point-contact Andreev reflection spectroscopy
• Peculiarities of the superconducting gaps and the electron-boson interaction in TmNi2B2C as seen by point-contact spectroscopy
• Superconductivity in Shear Strained Semiconductors