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.