Induced Superconducting Pairing in Integer Quantum Hall Edge Modes of InAs

Indium Arsenide (InAs) near surface quantum wells are ideal for the fabrication of semiconductor-superconductor heterostructures given that they allow for a strong hybridization between the two-dimensional states in the quantum well and the states in the superconductor. In this work we present results for the transport properties of heterojunctions in which the QH edge modes of the 2DEG formed in the InAs quantum well are proximitized to superconducting NbTiN. We observe a negative downstream resistance with a corresponding reduction of Hall (upstream) resistance. We analyze the experimental data using the Landauer-Büttiker formalism, generalized to allow for Andreev reflection processes, and by calculating the properties of the chiral Andreev edge states formed at the QH-superconductor interface. We obtain the maximum and minimum limit for the Andreev conversion averaged over the length of the QH-superconductor interface. Our analysis is consistent with a lower-bound for the averaged Andreev conversion of about 15%, a value that we estimate to be almost an order of magnitude larger than the values so far reported in the literature. We also study this negative resistance as a function of the QH-SC interface length in our devices.

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