Proximity-induced quasi-one-dimensional superconducting quantum anomalous Hall state: a promising scalable top-down approach towards localized Majorana modes

TL;DR

This study demonstrates that quasi-one-dimensional quantum anomalous Hall insulator nanoribbons with superconducting contacts can host zero-energy Majorana modes, offering a scalable platform for topological quantum computing.

Contribution

The paper introduces a scalable top-down fabrication approach for QAHI nanoribbons with superconducting contacts, providing experimental evidence of potential Majorana modes.

Findings

Observation of multiple in-gap conductance peaks evolving into a ZBCP with magnetic field

Experimental data consistent with Majorana zero modes in QAHI nanoribbons

Theoretical simulations support the transition from multi-channel to single-channel regimes

Abstract

In this work, ~100 nm wide quantum anomalous Hall insulator (QAHI) nanoribbons are etched from a two-dimensional QAHI film. One part of the nanoribbon is covered with superconducting Nb, while the other part is connected to an Au lead via two-dimensional QAHI regions. Andreev reflection spectroscopy measurements were performed, and multiple in-gap conductance peaks were observed in three different devices. In the presence of an increasing magnetic field perpendicular to the QAHI film, the multiple in-gap peak structure evolves into a single zero-bias conductance peak (ZBCP). Theoretical simulations suggest that the measurements are consistent with the scenario that the increasing magnetic field drives the nanoribbons from a multi-channel occupied regime to a single channel occupied regime, and that the ZBCP may be induced by zero energy Majorana modes as previously predicted [24]. Although further experiments are needed to clarify the nature of the ZBCP, we provide initial evidence that quasi-1D QAHI nanoribbon/superconductor heterostructures are new and promising platforms for realizing zero-energy Majorana modes.