Josephson phenomena in Van der Waals heterostructures

It is well established that a dissipationless supercurrent can flow across a junction at the interface between two superconductors due to a phenomenon known as the Josephson effect. This concept has recently been extended to 2D superconductors, where Josephson effects have been successfully measured at the interface between two misaligned NbSe2 flakes [1]. In this talk we discuss progress made in the formation of Josephson junctions between electrodes with different superconducting order parameters by two methods; homojunctions formed by stacking two exfoliated flakes of the same superconductor with a well-defined twist angle, and heterojunctions formed by stacking two different superconductors (eg. NbSe2, NbS2, BSSCO). These structures behave as underdamped Josephson junctions, exhibiting strong zero-bias supercurrents as well as clear signatures of the superconducting gaps. Finally, we will discuss the applications of this approach to the formation of more complex superconducting devices such as superconducting quantum interferometer devices (SQUIDS).

[1] N. Yabuki et al Nature Communications 7:10616 (2016)