Josephson effect between electron-doped and hole-doped iron pnictide single crystals

TL;DR

This paper reports the observation of the Josephson effect between electron-doped and hole-doped iron pnictide single crystals, demonstrating potential for phase-sensitive studies and device applications in iron-based superconductors.

Contribution

It is the first demonstration of the Josephson effect in p-n bicrystal structures of iron pnictides, enabling new phase-sensitive experiments.

Findings

Resistively-shunted junction characteristics observed in I-V curves

Ac Josephson effect confirmed under microwave irradiation

Critical current modulated by in-plane magnetic field

Abstract

We have observed the Josephson effect in junctions formed between single crystals of SrFe1.74Co0.26As2 and Ba0.23K0.77Fe2As2. I-V curves showed resistively-shunted junction characteristics, and the ac Josephson effect was observed under microwave irradiation. By applying an in-plane magnetic field, the critical current is completely modulated and shows a relatively symmetric diffraction pattern, consistent with the intermediate junction limit. The observation of the Josephson effect in the p-n bicrystal structure not only has significant implications for designing phase-sensitive junctions to probe the pairing symmetry of iron pnictide superconductors, but also represents an important step in developing all iron pnictide devices for applications.