Strong Superconducting Proximity Effect in Pb-Bi2Te3 Hybrid Structures

To study the interface between a conventional superconductor and a topological insulator, we fabricated Pb-Bi 2 Te 3 -Pb lateral and sandwiched junctions and performed electron transport measurements down to low temperatures. The results show that there is a strong superconducting proximity effect between Bi 2 Te 3 and Pb, as that a supercurrent can be established along the thickness direction of the Bi 2 Te 3 flakes (100~300 nm thick) at a temperature very close to the superconducting T c of Pb. Moreover, a Josephson current can be established over several microns in the lateral direction between two Pb electrodes on the Bi 2 Te 3 surface. We have further demonstrated that superconducting quantum interference devices can be constructed based on the proximity-effect-induced superconductivity. The critical current of the devices exhibits s -wave-like interference and Fraunhofer diffraction patterns. With improved designs, Josephson devices of this type would provide a test-bed for exploring novel phenomena such as Majorana fermions in the future.