Novel self-epitaxy for inducing superconductivity in the topological insulator (Bi1-xSbx)2Te3

Abstract

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 (Bi${}_{1-x}$Sb${}_x$)${}_2$Te${}_3$ leads to an epitaxial self-formation of PdTe${}_2$ 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 (Bi${}_{1-x}$Sb${}_x$)${}_2$Te${}_3$. This self-epitaxy phenomenon can be conveniently used for fabricating TI-based superconducting nanodevices to address the superconducting proximity effect in TIs.

9 pages total, 7 pages of main text with 4 figures, 2 pages of Supplemental Material with 2 figures