All Magnesium diboride Josephson Junctions with MgO and native oxide barriers

TL;DR

This paper reports on the fabrication and characterization of all-MgB2 Josephson junctions with MgO and native-oxide barriers, revealing different electrical behaviors and confirming theoretical models for MgO-based junctions.

Contribution

It introduces all-MgB2 Josephson junctions with MgO and native-oxide barriers, analyzing their electrical properties and behavior at various temperatures.

Findings

MgO barriers produce hysteretic I-V curves similar to underdamped junctions.

Critical current dependence on temperature matches Ambegaokar-Baratoff theory.

Native-oxide barriers show subgap features and no supercurrent despite superconducting gaps.

Abstract

We present results on all-MgB2 tunnel junctions, where the tunnel barrier is deposited MgO or native-oxide of base electrode. For the junctions with MgO, the hysteretic I-V curve resembles a conventional underdamped Josephson junction characteristic with critical current-resistance product nearly independent of the junction area. The dependence of the critical current with temperature up to 20 K agrees with the [Ambegaokar and Baratoff, Phys. Rev. Lett. 10, 486 (1963)] expression. For the junctions with native-oxide, conductance at low bias exhibits subgap features while at high bias reveals thick barriers. As a result no supercurrent was observed in the latter, despite the presence of superconducting-gaps to over 30 K.