Berlin 2024 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 31: Focus Session: Evolution of Topological Materials into Superconducting Nanodevices II (joint session HL/TT)

HL 31.1: Vortrag

Mittwoch, 20. März 2024, 11:45–12:00, EW 202

Induced superconducting correlations in the quantum anomalous Hall insulator — •Anjana Uday1, Gertjan Lippertz1,2, Kristof Moors3, Henry F. Legg4, Rikkie Joris2, Andrea Bliesener1, Lino M. C. Pereira2, Alexey Taskin1, and Yoichi Ando11Physics Institute II, University of Cologne, Köln, Germany — 2KU Leuven, Quantum Solid State Physics, Leuven, Belgium — 3Peter Grünberg Institute 9, Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance, Jülich, Germany — 4Department of Physics, University of Basel, Basel, Switzerland

Crossed Andreev reflection (CAR) has been reported in a hybrid quantum Hall (QH)/Superconductor (SC) system [1]. Similar experiments would be of great interest for quantum anomalous Hall (QAH) systems. It has been predicted that if Cooper pairing is induced in a QAH insulator, the system turns into a stereotypical spinless chiral p-wave superconductor associated with chiral Majorana edge states. In the QAH/SC system superconductivity can be suppressed by applying a magnetic field while keeping the 1D chiral edge state intact. Here we report the observation of crossed Andreev reflection (CAR) across a narrow superconducting Nb electrode contacting the chiral edge state of a QAHI, evinced by a negative nonlocal voltage measured downstream from the grounded Nb electrode. By changing the Nb width, the characteristic length of the CAR process is identified to be about 100 nm, which is three times longer than the superconducting correlation length in Nb.

[1] Lee et al., Nat. Phys., 13 (2017) 693-698

Keywords: Crossed Andreev reflection; quantum anomalous Hall effect; magnetic topological insulator; superconducting proximity effect

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