Andreev Reflection in the Quantum Hall Regime at an Al/InAs Junction on a Cleaved Edge.
basic_science · Level V
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- Record sourced from PubMed, PMID 39505712.
- Also identified by DOI 10.1021/acs.nanolett.4c04223.
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Abstract
We have fabricated a superconductor/semiconductor junction composed of Al and InAs using cleaved edge overgrowth. By exploiting the unique geometry with a thin Al/Pt/Al trilayer formed on the side surface of an in situ cleaved InAs quantum well heterostructure wafer, we achieve a superconducting critical field of ∼5 T, allowing superconductivity and quantum Hall (QH) effects to coexist down to filling factor ν = 3. Andreev reflection at zero magnetic field shows a conductance enhancement limited solely by the Fermi velocity mismatch, demonstrating a virtually barrier-free junction. Bias spectroscopy in the QH regime reveals the opening of a superconducting gap, with the reduced downstream resistance indicating electron-hole Andreev conversion. Our results, obtained in a new experimental regime characterized by a clean edge-contacted junction with a superconducting electrode narrower than the coherence length, open new avenues for both theoretical and experimental studies of the interplay between superconductivity and QH effects.