Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session C52: Topological Superconductivity: 2D Materials and Heterostructures
3:00 PM–6:00 PM,
Monday, March 15, 2021
Sponsoring Unit: DMP
Chair: Anand Bhattacharya, Argonne National Laboratory
Abstract: C52.00006 : Quanum Hall - superconductor hybrid devices*
4:24 PM–5:00 PM
Anne M Draelos
Ming Tso Wei
(Appalachian State University)
Harold U Baranger
1) We have developed graphene Josephson junctions with self-aligned side gates, which enable full control over the electrostatic potential near the sample edges. The gates allow us to tune the local electron density in a wide range, in particular inducing counterpropagating quantum Hall edge states along either side gate. The close spacing between these states allows them to efficiently couple through Andreev reflections and carry supercurrent. When both side gates are applied, superconducting channels are created on both sides of the junction, thereby realizing a gate-tunable quantum Hall-based SQUID.
2) We observe direct signatures of chiral Andreev edge states (CAES) – single particle modes running along the superconductor - quantum Hall interfaces. Semi-classically, the CAES can be interpreted as a result of multiple Andreev reflections of a single electron/hole skipping along the interface. Experimentally, we observe fluctuations of the signal propagating along the superconducting contact and interpret them in terms of interference between the CAES.
**Transport measurements conducted by L.Z., E.G.A., and A.S. were supported by the DOE Award No. de-sc 0002765. Lithographic fabrication and samples characterization was performed by L.Z., M.-T. W., and A.S. with the support of NSF award DMR-1743907. The measurement setup was developed by A.W.D., T.L., and G.F. with the support of ARO Award W911NF-16-1-0122. Numerical simulations conducted by A.B. and H.U.B. were supported by the DOE Award No. de-sc0005237. H.L. and F.A. acknowledge the ARO Award W911NF-16-1- 0132. K.W. and T.T. acknowledge support from JSPS KAKENHI Grant Number JP15K21722.
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