Interface shape dependent interference patterns of NbSe2 heterostructure Josephson junctions

The superconducting critical current oscillations as a function of magnetic field were previously observed in heterostructure Josephson junctions fabricated by twisting and stacking superconducting van der Waals materials. The interference patterns, however, are often distorted. Here, we report a model for understanding the shape of oscillation patterns in heterostructure Josephson junctions. To this end, we fabricated Josephson junctions by stacking two bulk superconducting 2H-NbSe2 flakes on top of each other. We were able to control the junction fabricated to be either diffusive or clean by varying the temperature during the stacking process. The measured magnetic field dependence of the critical current exhibits either a Gaussian decay or a clear oscillatory pattern with maxima and minima. We identify the shape of the interference patterns not only depends on the type of junction; they are also strongly dictated by field orientation and interface geometry. This is a consequences of the fact that heterostructure junctions often have inhomogeneous widths that extend along the field direction. We calculate the expected interference pattern from the junction geometry by applying our model and find excellent agreement to our experimental data.

Automated summary

Researchers have successfully controlled the type of junction by stacking 2H-NbSe2 flakes and found that the shape of interference patterns is not only determined by the type of junction, but also by the magnetic field orientation and interface geometry.