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Title: Absence of evidence for chiral Majorana modes in quantum anomalous Hall-superconductor devices

Journal Article · · Science

A quantum anomalous Hall (QAH) insulator coupled to an s-wave superconductor is predicted to harbor chiral Majorana modes. A recent experiment interprets the half-quantized two-terminal conductance plateau as evidence for these modes in a millimeter-size QAH-niobium hybrid device. However, non-Majorana mechanisms can also generate similar signatures, especially in disordered samples. Here, we studied similar hybrid devices with a well-controlled and transparent interface between the superconductor and the QAH insulator. When the devices are in the QAH state with well-aligned magnetization, the two-terminal conductance is always half-quantized. Our experiment provides a comprehensive understanding of the superconducting proximity effect observed in QAH-superconductor hybrid devices and shows that the half-quantized conductance plateau is unlikely to be induced by chiral Majorana fermions in samples with a highly transparent interface.

Sponsoring Organization:
USDOE
Grant/Contract Number:
SC0019064
OSTI ID:
1580806
Alternate ID(s):
OSTI ID: 1803543
Journal Information:
Science, Journal Name: Science Journal Issue: 6473 Vol. 367; ISSN 0036-8075
Publisher:
American Association for the Advancement of Science (AAAS)Copyright Statement
Country of Publication:
United States
Language:
English

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