Exploring Topological Interfacial Superconductivity in Quantum Anomalous Hall/Iron Chalcogenide Heterostructures

Cui-Zu Chang

Professor of Physics, The Pennsylvania State University

The search for the chiral topological superconducting (TSC) phase has attracted great interest due to its fundamental importance and potential applications in topological quantum computation. A chiral TSC phase is predicted to emerge when a quantum anomalous Hall (QAH) insulator is coupled to a conventional superconductor, creating an exotic state that can host Majorana quasiparticles. Realizing such hybrid structures has been challenging because the magnetic nature of QAH materials typically suppresses superconductivity at their interface. With support from the current DOE grant, we have discovered interface-induced superconductivity in heterostructures that combine a ferromagnetic topological insulator, Cr-doped (Bi,Sb)2Te3, with an antiferromagnetic iron chalcogenide, FeTe. These QAH/FeTe heterostructures provide a promising platform for exploring the chiral TSC phase and chiral Majorana modes. In this renewal project, we will use molecular beam epitaxy (MBE) to synthesize FeTe films and related heterostructures, and employ in situ scanning tunneling microscopy/spectroscopy, angle-resolved photoemission spectroscopy, and electrical transport measurements to investigate the mechanism of the emergent superconductivity.