Topological Transition in a 3nm Thick Al Film Grown by Molecular Beam Epitaxy

Abstract

We have performed detailed transport measurements on a 3nm thick (as-grown) Al film on GaAs prepared by molecular beam epitaxy (MBE). Such an epitaxial film grown on a GaAs substrate shows the Berezinskii-Kosterlitz-Thouless (BKT) transition, a topological transition in two dimensions. Our experimental data shows that the MBE-grown Al nanofilm is an ideal system for probing interesting physical phenomena such as the BKT transition and superconductivity. The increased superconductor transition temperature (similar to 2.4K) compared to that of bulk Al (1.2K), together with the ultrathin film quality, may be advantageous for future superconductor-based quantum devices and quantum information technology.