Interference, diffraction, and diode effects in superconducting array based on bismuth antimony telluride topological insulator

It is well-known in optics that the spectroscopic resolution of a diffraction grating is much better compared to an interference device having just two slits, as in Young’s famous double-slit experiment. On the other hand, it is well known that a classical superconducting quantum interference device (SQUID) is analogous to the optical double-slit experiment. Here we report experiments and present a model describing a superconducting analogue to the diffraction grating, namely an array of superconducting islands positioned on a topological insulator film Bi_0.8Sb_1.2Te₃. In the limit of an extremely weak field, of the order of one vortex per the entire array, such devices exhibit a critical current peak that is much sharper than the analogous peak of an ordinary SQUID. Therefore, such arrays can be used as sensitive absolute magnetic field sensors. A key finding is that the device acts as a superconducting diode, controlled by magnetic field.