Interfacial Structure and Electronic Properties of FeSe/GaAs (001) Heterostructures grown by molecular beam epitaxy

Interfaces between high-temperature superconductors (SC) and large spin-orbit coupling (SOC) semiconductors are a platform for realizing topological superconductivity. Our recent first-principles and model Hamiltonian theory identifies thin films of the high-temperature superconductor FeSe, grown on Bi-doped GaAs (001), as a promising system [1, 2]. However, the synthesis of such heterostructures presents significant challenges, including lattice mismatch and complex interfacial reactions. Here, we demonstrate the synthesis of FeSe on GaAs (001) by molecular beam epitaxy (MBE), designed to probe the fundamental challenges of this heterointerface. We will report on a systematic study of the atomic and electronic structure of the FeSe/GaAs interface, using high-resolution TEM to resolve its atomic configuration and its resulting transport properties. This work is benchmarked against predictions from density functional theory and dynamical mean field theory (DFT+eDMFT), which predict stable interfacial configurations and reveal a strong sensitivity of the electronic structure to Se-As intermixing. Our FeSe/GaAs heterostructures provide a model platform for understanding and engineering the interface between correlated superconductors and III-V semiconductors.

[1] Georges, Antoine, et al. Reviews of modern physics 68.1 (1996): 13.

[2] Kotliar, Gabriel, et al. Reviews of Modern Physics 78.3 (2006): 865-951.