Subharmonic gap structures and Josephson effect in MgB2∕Nb microconstrictions
F. Giubileo, M. Aprili, F. Bobba, S. Piano, A. Scarfato, A. M. Cucolo
DOI 10.1103/PhysRevB.72.174518 · Physical Review B
Active bibliographic source — not scientific approval
Bibliographic access preserves source history; it does not approve extracted materials or validate reported claims. Review warnings on each occurrence separately.
Abstract
Superconducting microconstrictions between Nb tips and high-quality MgB2 pellets have been realized by means of a point-contact inset, driven by a micrometric screw. Measurements of the current-voltage characteristics and of the dynamical conductance versus bias have been performed in the temperature range between 4.2K and 500K. Above the Nb critical temperature TCNb, the conductance of the MgB2/normal-metal constrictions behaves as predicted by the Blonder-Tinkham-Klapwijk model for low-resistance contacts while high-resistance junctions show quasiparticle tunneling characteristics. Consistently, from the whole set of data we infer the value Δπ=2.5±0.2meV for the three-dimensional (3D) gap of MgB2. Below TCNb, low-resistance contacts show Josephson current and subharmonic gap structures, due to multiple Andreev reflections. Simultaneous observations of both features unambiguously indicate a coupling of the 3D band of MgB2 with the Nb superconducting order parameter. We found that the temperature dependence of the Josephson critical current follows the classical Ambegaokar-Baratoff behavior with a value ICRN=(2.1±0.1)meV at low temperatures.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 39 | Pressure not reported | unknown |
| MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 38.8 | Pressure not reported | zero_resistance |
| Nb Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 9.2 | Pressure not reported | unknown |
Similar papers
Evidence for Two Superconducting Energy Gaps in MgB2 by Point-Contact Spectroscopy
similarity 0.95P. Szabó et al.
Source status unknown — claims are unverified
Quantum waveguide theory of the Josephson effect in multiband superconductors
similarity 0.94C. Nappi et al.
Source status unknown — claims are unverified
Monte Carlo study on phase transitions of two-band Josephson networks with superconducting grains
similarity 0.94Jie Li & Hai Huang
Source status unknown — claims are unverified
Josephson Effect in MgB2 Break Junctions
similarity 0.93R. S. Gonnelli et al.
Source status unknown — claims are unverified
Strong phase coherence and vortex matter in a fractal system with proximity-induced superconductivity
similarity 0.93Nanami Teramachi et al.
Source status unknown — claims are unverified
Josephson effects between multigap and single-gap superconductors
similarity 0.93D. F. Agterberg et al.
Source status unknown — claims are unverified