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

Morteza Kayyalha, Di Xiao, Ruoxi Zhang, Jaeho Shin, Jue Jiang, Fei Wang, Yi Fan Zhao, Run Xiao, Ling Zhang, Kajetan M. Fijalkowski, Pankaj Mandal, Martin Winnerlein, Charles Gould, Qi Li, Laurens W. Molenkamp, Moses H.W. Chan, Nitin Samarth, Cui Zu Chang

Research output: Contribution to journalArticle

Abstract

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.

Original languageEnglish (US)
Pages (from-to)64-67
Number of pages4
JournalScience
Volume367
Issue number6473
DOIs
StatePublished - Jan 3 2020

Fingerprint

Equipment and Supplies
Niobium
Superconductivity

All Science Journal Classification (ASJC) codes

  • General

Cite this

Kayyalha, Morteza ; Xiao, Di ; Zhang, Ruoxi ; Shin, Jaeho ; Jiang, Jue ; Wang, Fei ; Zhao, Yi Fan ; Xiao, Run ; Zhang, Ling ; Fijalkowski, Kajetan M. ; Mandal, Pankaj ; Winnerlein, Martin ; Gould, Charles ; Li, Qi ; Molenkamp, Laurens W. ; Chan, Moses H.W. ; Samarth, Nitin ; Chang, Cui Zu. / Absence of evidence for chiral Majorana modes in quantum anomalous Hall-superconductor devices. In: Science. 2020 ; Vol. 367, No. 6473. pp. 64-67.
@article{32298d51a7014e7d9afd8dcfc11b0ad7,
title = "Absence of evidence for chiral Majorana modes in quantum anomalous Hall-superconductor devices",
abstract = "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.",
author = "Morteza Kayyalha and Di Xiao and Ruoxi Zhang and Jaeho Shin and Jue Jiang and Fei Wang and Zhao, {Yi Fan} and Run Xiao and Ling Zhang and Fijalkowski, {Kajetan M.} and Pankaj Mandal and Martin Winnerlein and Charles Gould and Qi Li and Molenkamp, {Laurens W.} and Chan, {Moses H.W.} and Nitin Samarth and Chang, {Cui Zu}",
year = "2020",
month = "1",
day = "3",
doi = "10.1126/science.aax6361",
language = "English (US)",
volume = "367",
pages = "64--67",
journal = "Science",
issn = "0036-8075",
publisher = "American Association for the Advancement of Science",
number = "6473",

}

Kayyalha, M, Xiao, D, Zhang, R, Shin, J, Jiang, J, Wang, F, Zhao, YF, Xiao, R, Zhang, L, Fijalkowski, KM, Mandal, P, Winnerlein, M, Gould, C, Li, Q, Molenkamp, LW, Chan, MHW, Samarth, N & Chang, CZ 2020, 'Absence of evidence for chiral Majorana modes in quantum anomalous Hall-superconductor devices', Science, vol. 367, no. 6473, pp. 64-67. https://doi.org/10.1126/science.aax6361

Absence of evidence for chiral Majorana modes in quantum anomalous Hall-superconductor devices. / Kayyalha, Morteza; Xiao, Di; Zhang, Ruoxi; Shin, Jaeho; Jiang, Jue; Wang, Fei; Zhao, Yi Fan; Xiao, Run; Zhang, Ling; Fijalkowski, Kajetan M.; Mandal, Pankaj; Winnerlein, Martin; Gould, Charles; Li, Qi; Molenkamp, Laurens W.; Chan, Moses H.W.; Samarth, Nitin; Chang, Cui Zu.

In: Science, Vol. 367, No. 6473, 03.01.2020, p. 64-67.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Absence of evidence for chiral Majorana modes in quantum anomalous Hall-superconductor devices

AU - Kayyalha, Morteza

AU - Xiao, Di

AU - Zhang, Ruoxi

AU - Shin, Jaeho

AU - Jiang, Jue

AU - Wang, Fei

AU - Zhao, Yi Fan

AU - Xiao, Run

AU - Zhang, Ling

AU - Fijalkowski, Kajetan M.

AU - Mandal, Pankaj

AU - Winnerlein, Martin

AU - Gould, Charles

AU - Li, Qi

AU - Molenkamp, Laurens W.

AU - Chan, Moses H.W.

AU - Samarth, Nitin

AU - Chang, Cui Zu

PY - 2020/1/3

Y1 - 2020/1/3

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=85077437125&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85077437125&partnerID=8YFLogxK

U2 - 10.1126/science.aax6361

DO - 10.1126/science.aax6361

M3 - Article

C2 - 31896711

AN - SCOPUS:85077437125

VL - 367

SP - 64

EP - 67

JO - Science

JF - Science

SN - 0036-8075

IS - 6473

ER -