Novel self-epitaxy for inducing superconductivity in the topological insulator <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>(</mml:mo><mml:msub><mml:mi>Bi</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi>Sb</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:msub><mml:mrow><mml:mo>)</mml:mo></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Te</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>
Mengmeng Bai, Fan Yang, Martina Luysberg, Junya Feng, Andrea Bliesener, Gertjan Lippertz, A. A. Taskin, Joachim Mayer, Yoichi Ando
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 ${({\mathrm{Bi}}_{1\ensuremath{-}x}{\mathrm{Sb}}_{x})}_{2}{\mathrm{Te}}_{3}$ leads to an epitaxial self-formation of $\mathrm{Pd}{\mathrm{Te}}_{2}$ superconductor having the superconducting transition temperature of $\ensuremath{\sim}1$ K. This self-formed superconductor proximitizes the TI, which is confirmed by the appearance of a supercurrent in Josephson-junction devices made on ${({\mathrm{Bi}}_{1\ensuremath{-}x}{\mathrm{Sb}}_{x})}_{2}{\mathrm{Te}}_{3}$. This self-epitaxy phenomenon can be conveniently used for fabricating TI-based superconducting nanodevices to address the superconducting proximity effect in TIs.