Interface driven superconductivity in topological insulator Fe-based superconductor heterostructures

by Dr Matthew Brahlek (Oak Ridge National Lab.)

Wednesday 21 Aug 2024, 14:00 → 15:00 Europe/Zurich

SZ-WBGB/019

Realizing exotic forms of superconductivity through epitaxially integrating high-transition-temperature (T_C) superconductors with topological insulators can open new paths for quantum-based applications. In this talk, I will discuss how understanding molecular beam epitaxy growth has enable the creation interfaces with idealized spin-momentum locking and superconductivity as well as revealing hidden phenomena. Specifically, I will discuss how tailoring the synthesis of either member facilitates aligning the spin-momentum locked topological bandstructure of Bi₂Te₃ with the superconducting states of Fe(Te,Se). Furthermore, I will show how systematically reducing the Bi₂Te₃ can stabilize another topological phase, Bi₄Te₃, which when integrated with Fe(Te,Se) shifts the doping phase diagram and stabilizes superconductivity in the clean, low Se-doping regime. Changing the topological phase to Bi₄Te₃, moreover, is critical to stabilize superconductivity in monolayer Fe(Te,Se), where the strongest interactions of the topological and superconductivity states occurs. This novel route for epitaxial phase control at topological/superconducting interfaces provides new insight into the nature of unconventional superconductivity while being a new platform for identifying and utilizing new electronic phases.