Quantum confinement of the Dirac surface states in topological-insulator nanowires

Felix Münning; Oliver Breunig; Henry F. Legg; Stefan Roitsch; Dingxun Fan; Matthias Rößler; Achim Rosch; Yoichi Ando

doi:10.1038/s41467-021-21230-3

Quantum confinement of the Dirac surface states in topological-insulator nanowires

Felix Münning, Oliver Breunig, Henry F. Legg, Stefan Roitsch, Dingxun Fan, Matthias Rößler, Achim Rosch, Yoichi Ando^*

^*Corresponding author for this work

School of Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

Abstract

The non-trivial topology of three-dimensional topological insulators dictates the appearance of gapless Dirac surface states. Intriguingly, when made into a nanowire, quantum confinement leads to a peculiar gapped Dirac sub-band structure. This gap is useful for, e.g., future Majorana qubits based on TIs. Furthermore, these sub-bands can be manipulated by a magnetic flux and are an ideal platform for generating stable Majorana zero modes, playing a key role in topological quantum computing. However, direct evidence for the Dirac sub-bands in TI nanowires has not been reported so far. Here, using devices fabricated from thin bulk-insulating (Bi_1−xSb_x)₂Te₃ nanowires we show that non-equidistant resistance peaks, observed upon gate-tuning the chemical potential across the Dirac point, are the unique signatures of the quantized sub-bands. These TI nanowires open the way to address the topological mesoscopic physics, and eventually the Majorana physics when proximitized by an s-wave superconductor.

Original language	English
Article number	1038
Number of pages	6
Journal	Nature Communications
Volume	12
DOIs	https://doi.org/10.1038/s41467-021-21230-3
Publication status	Published - 15 Feb 2021

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Cite this

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title = "Quantum confinement of the Dirac surface states in topological-insulator nanowires",

abstract = "The non-trivial topology of three-dimensional topological insulators dictates the appearance of gapless Dirac surface states. Intriguingly, when made into a nanowire, quantum confinement leads to a peculiar gapped Dirac sub-band structure. This gap is useful for, e.g., future Majorana qubits based on TIs. Furthermore, these sub-bands can be manipulated by a magnetic flux and are an ideal platform for generating stable Majorana zero modes, playing a key role in topological quantum computing. However, direct evidence for the Dirac sub-bands in TI nanowires has not been reported so far. Here, using devices fabricated from thin bulk-insulating (Bi1−xSbx)2Te3 nanowires we show that non-equidistant resistance peaks, observed upon gate-tuning the chemical potential across the Dirac point, are the unique signatures of the quantized sub-bands. These TI nanowires open the way to address the topological mesoscopic physics, and eventually the Majorana physics when proximitized by an s-wave superconductor.",

author = "Felix M{\"u}nning and Oliver Breunig and Legg, \{Henry F.\} and Stefan Roitsch and Dingxun Fan and Matthias R{\"o}{\ss}ler and Achim Rosch and Yoichi Ando",

note = "Funding: This project has received funding from the European Research Council (ERC) under the European Union{\textquoteright}s Horizon 2020 research and innovation programme (grant agreement no. 741121) and was also funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under CRC 1238—277146847 (Subprojects A04, B01, and C02) as well as under Germany{\textquoteright}s Excellence Strategy—Cluster of Excellence Matter and Light for Quantum Computing (ML4Q) EXC 2004/1 - 390534769. O.B. acknowledges the support from the Quantum Matter and Materials Program at the University of Cologne funded by the German Excellence Initiative.",

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AU - Münning, Felix

AU - Breunig, Oliver

AU - Legg, Henry F.

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AU - Rößler, Matthias

AU - Rosch, Achim

AU - Ando, Yoichi

N1 - Funding: This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 741121) and was also funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under CRC 1238—277146847 (Subprojects A04, B01, and C02) as well as under Germany’s Excellence Strategy—Cluster of Excellence Matter and Light for Quantum Computing (ML4Q) EXC 2004/1 - 390534769. O.B. acknowledges the support from the Quantum Matter and Materials Program at the University of Cologne funded by the German Excellence Initiative.

PY - 2021/2/15

Y1 - 2021/2/15

N2 - The non-trivial topology of three-dimensional topological insulators dictates the appearance of gapless Dirac surface states. Intriguingly, when made into a nanowire, quantum confinement leads to a peculiar gapped Dirac sub-band structure. This gap is useful for, e.g., future Majorana qubits based on TIs. Furthermore, these sub-bands can be manipulated by a magnetic flux and are an ideal platform for generating stable Majorana zero modes, playing a key role in topological quantum computing. However, direct evidence for the Dirac sub-bands in TI nanowires has not been reported so far. Here, using devices fabricated from thin bulk-insulating (Bi1−xSbx)2Te3 nanowires we show that non-equidistant resistance peaks, observed upon gate-tuning the chemical potential across the Dirac point, are the unique signatures of the quantized sub-bands. These TI nanowires open the way to address the topological mesoscopic physics, and eventually the Majorana physics when proximitized by an s-wave superconductor.

AB - The non-trivial topology of three-dimensional topological insulators dictates the appearance of gapless Dirac surface states. Intriguingly, when made into a nanowire, quantum confinement leads to a peculiar gapped Dirac sub-band structure. This gap is useful for, e.g., future Majorana qubits based on TIs. Furthermore, these sub-bands can be manipulated by a magnetic flux and are an ideal platform for generating stable Majorana zero modes, playing a key role in topological quantum computing. However, direct evidence for the Dirac sub-bands in TI nanowires has not been reported so far. Here, using devices fabricated from thin bulk-insulating (Bi1−xSbx)2Te3 nanowires we show that non-equidistant resistance peaks, observed upon gate-tuning the chemical potential across the Dirac point, are the unique signatures of the quantized sub-bands. These TI nanowires open the way to address the topological mesoscopic physics, and eventually the Majorana physics when proximitized by an s-wave superconductor.

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Quantum confinement of the Dirac surface states in topological-insulator nanowires

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