Coexistence of induced superconductivity and quantum Hall states in InSb nanosheets

Abstract

Hybrid superconducting devices based on high-mobility two-dimensional electron gases with strong spin-orbit coupling are considered to offer a flexible and scalable platform for topological quantum computation. Here, we report the realization and electrical characterization of hybrid devices based on high-quality InSb nanosheets and superconducting niobium (Nb) electrodes. In these hybrid devices, we observe gate-tunable proximity-induced supercurrent and multiple Andreev reflections, indicating a transparent Nb-InSb nanosheet interface. The high critical magnetic field of Nb combined with high-mobility InSb nanosheets allows us to exploit the transport properties in the exotic regime where the superconducting proximity effect coexists with the quantum Hall effect. Transport spectroscopy measurements in such a regime reveal an enhancement of the conductance at the quantum Hall plateaus, accompanied by a pronounced zero-bias peak in the differential conductance. We discuss that these features originate from the formation of Andreev edge states at the superconductor-InSb nanosheet interface in the quantum Hall regime. In addition to shedding light on the interplay between superconductivity and quantum Hall effect, our work opens a new possibility to develop hybrid superconducting devices based on 2D semiconductor nanosheets with strong spin-orbit coupling.