Superconducting quantum interference devices of (Bi_1-xSb_x)₂Se₃ topological insulator nanoribbons

Topological insulator (TI) nanoribbons in contact with conventional superconducting electrodes can be a useful platform to generate a Majoarana bound state. As an evidence of the Majorana state, anomalous 4π current-phase relation is theoretically expected in a superconducting proximity junction of topological insulator. Here, we report the fabrication and measurement of a superconducting quantum interference device (SQUID) made of (Bi_1-xSb_x)₂Se₃ TI nanoribbon. When we applied a magnetic field perpendicular to the substrate, we observed the periodic oscillations of supercurrent flow and the periodicity coincides with a magnetic flux quantum of h/2e.
Under a magnetic field parallel to the TI nanoribbon, the axial magnetoresistance data exhibited periodic oscillations with a period of h/e, which was due to the Aharonov-Bohm oscillations along the topological surface state of the nanoribbon.