BaFe_{1.8}Co_{0.2}As_2 thin film hybrid Josephson junctions

TL;DR

This paper reports on the fabrication and characterization of hybrid Josephson junctions using BaFe_{1.8}Co_{0.2}As_2 thin films, revealing their superconducting properties and potential for superconducting device applications.

Contribution

It introduces a new type of hybrid Josephson junction with iron pnictide electrodes and demonstrates their electrical characteristics and microwave response.

Findings

Junctions exhibit RSJ-like I-V characteristics up to 7.2K.

Observation of well-pronounced Shapiro steps at 10-18GHz.

Effective I_C R_N product of 6 μV at 4.2K.

Abstract

Josephson junctions with iron pnictides open the way for fundamental experiments on superconductivity in these materials and their application in superconducting devices. Here, we present hybrid Josephson junctions with a BaFe_{1.8}Co_{0.2}As_2 thin film electrode, an Au barrier and a PbIn counter electrode. The junctions show RSJ-like current-voltage characteristics up to the critical temperature of the counter electrode of about 7.2K. The temperature dependence of the critical current, IC, does not show an Ambegaokar-Baratoff behavior. Well-pronounced Shapiro steps are observed at microwave frequencies of 10-18GHz. Assuming an excess current, I_ex, of 200 {\mu}A at 4.2K we get an effective I_C R_N product of 6 {\mu}V.