Proximity-Induced Superconductivity in a Topological Insulator using an Fe-based Superconductor
ORAL
Abstract
Interest in the superconducting proximity effect (SPE) has recently been reignited by theoretical predictions that it could be used to achieve topological superconductivity. However, small proximity-induced gaps (Δind) of ~1 meV predominantly obtained using select few low-Tc superconductors have hindered the fundamental understanding of what drives the SPE across complex interfaces. We use molecular beam epitaxy to grow a prototypical topological insulator Bi2Te3 on a multi-gap high-Tc superconductor Fe(Te,Se), to achieve a significantly larger induced superconducting gap (Δind) and transition temperature (Tc) compared to studies. Interestingly, in contrast to previous hypothesis suggesting the importance of Fermi surface alignment in achieving superconducting proximity effect, we discover that Δind in Bi2Te3 is dictated by the superconducting gap in the momentum-mismatched parent superconductor’s Fermi surfaces. Our work suggests a concrete pathway to guide the synthesis of new heterostructures with larger Δind and higher Tc using Fe-based superconductors.
*We gratefully acknowledge the support from the Army Research Office Grant No. W911NF-17-1-0399 and the NSF Grant No. 1654041.
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Presenters
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He Zhao
- Boston Coll