Phys. Rev. Materials 4, 094801 (2020)
Novel self-epitaxy for inducing superconductivity in the topological insulator (Bi1−xSbx)2Te3
Mengmeng Bai 1,*, Fan Yang 1,2,*,†, Martina Luysberg 3,*, Junya Feng 1, Andrea Bliesener 1, Gertjan Lippertz 1,4, A. A. Taskin 1, Joachim Mayer 3, and Yoichi Ando 1,‡
1 Physics Institute II, University of Cologne, Zülpicher Str. 77, 50937 Köln, Germany
2 Center for Joint Quantum Studies and Department of Physics, School of Science, Tianjin University, Tianjin 300350, China
3 Ernst Ruska-Centre, Forschungszentrum Jülich, 52425 Jülich, Germany
4 KU Leuven, Quantum Solid State Physics, Celestijnenlaan 200D, 3001 Leuven, Belgium
* These authors contributed equally to this work.
Using the superconducting proximity effect for engineering a topological superconducting state in a topological insulator (TI) is a promising route to realize Majorana fermions. However, epitaxial growth of a superconductor on the TI surface to achieve a good proximity effect has been a challenge. We discovered that simply depositing Pd on thin films of the TI material (Bi1−xSbx )2Te3 leads to an epitaxial self-formation of PdTe2 superconductor having the superconducting transition temperature of ∼1 K. This self-formed superconductor proximitizes the TI, which is confirmed by the appearance of a supercurrent in Josephson-junction devices made on (Bi1−xSbx )2Te3. This self-epitaxy phenomenon can be conveniently used for fabricating TI-based superconducting nanodevices to address the superconducting proximity effect in TIs.