Proximity-effect-induced superconductivity in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">Bi</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">Te</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:mo>/</mml:mo><mml:mi mathvariant="normal">Fe</mml:mi><mml:msub><mml:mi mathvariant="normal">Se</mml:mi><mml:mrow><mml:mn>0.5</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi mathvariant="normal">Te</mml:mi><mml:mrow><mml:mn>0.5</mml:mn></mml:mrow></mml:msub></mml:math> thin-film heterostructures with different interface conditions
Yalin Zhang, Jingfeng Huang, Chunchen Zhang, Peng Wang, Zhihe Wang, Tong Wang, Zhongwen Xing, D. Y. Xing
Abstract
Proximity-effect-induced superconductivity is studied for high-quality ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}/\mathrm{Fe}{\mathrm{Se}}_{0.5}{\mathrm{Te}}_{0.5}$ (FST) thin-film heterostructures with atomically sharp interfaces and for ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}/{\mathrm{TiO}}_{2}$/FST heterostructures where ${\mathrm{TiO}}_{2}$ is the ultrathin buffer layer. Adjusting the buffer layer thickness from zero to several nanometers is used to simulate different interface conditions: strongly, weakly, and zero-coupled interfaces. It is found that, for the strongly coupled interface, both the ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$ thin film and the FST have almost the same magnitude as the superconducting pair potential; for the weakly coupled interface, the pairing potential of the ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$ thin film exhibits an approximately exponential decay with the ${\mathrm{TiO}}_{2}$ buffer layer thickness. Our experimental results can be explained qualitatively by several theories under different interface conditions.