Deliverable D4.2 : Josephson effect in a TI nanowire-based device

DELIVERABLE D4.2: Josephson effect in a TI nanowire-based device

Hybrid material systems with a conventional superconductor in proximity to a strong spin-orbit semiconductor or a Topological Insulator (TI) have recently acquired a vast interest due to their potential to host exotic phenomena.  In a multimode hybrid TI Josephson junction with two terminal geometry, Majorana physics manifests as peculiar properties of a part of the Andreev bound states carrying the Josephson current. They give rise to an unconventional 4π periodic current phase relation (CPR) coexisting with a 2π periodic CPR resulting from the conventional Andreev bound states. The relative weight between the 4π and 2π periodic Andreev bound states increases with the transparency of the junction and, in general, by reducing the number of channels. We make use of Al-Bi2Se3-Al junctions fabricated using TINRs grown by physical vapor deposition. To extract the current phase relation of our TI-junction, we utilize an asymmetric dc-Superconducting Quantum Interference Device (SQUID) measurement technique.