Magnetic field-bias current interplay in HgTe-based three-terminal Josephson junctions

TL;DR

This study explores how magnetic fields and bias currents influence the behavior of HgTe-based three-terminal Josephson junctions, revealing tunable interference patterns and enhanced diode efficiency through experimental and simulation analysis.

Contribution

It demonstrates the joint effect of magnetic field and bias current on Josephson interference patterns and introduces a regime of high Josephson diode efficiency in multi-terminal junctions.

Findings

Magnetic field induces crossover between SQUID-like and Fraunhofer-like patterns.

Bias current controls symmetry and deformation of critical current contours.

Achieved Josephson diode efficiency up to approximately 0.8.

Abstract

We investigate HgTe/Nb-based three-terminal Josephson junctions in T-shaped and X-shaped geometries and their critical current contours (CCCs). By decomposing the CCCs into the contributions from individual junctions, we uncover how bias current and magnetic field jointly determine the collective Josephson behavior. A perpendicular magnetic field induces a tunable crossover between SQUID-like and Fraunhofer-like interference patterns, controlled by the applied bias. Moreover, magnetic flux produces pronounced deformations of the CCC, enabling symmetry control in the $(I_1,I_2)$ plane. Remarkably, we identify a regime of strongly enhanced Josephson diode efficiency, reaching values up to $\eta\approx 0.8$ at low bias and magnetic field. The experimental results are quantitatively reproduced by resistively shunted junction (RSJ) simulations, which capture the coupled dynamics of current and flux in these multi-terminal superconducting systems.