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Behner G, Jalil AR, Heffels D, Kölzer J, Moors K, Mertens J, Zimmermann E, Mussler G, Schüffelgen P, Lüth H, Grützmacher D, Schäpers T. Aharonov-Bohm Interference and Phase-Coherent Surface-State Transport in Topological Insulator Rings. NANO LETTERS 2023. [PMID: 37399545 PMCID: PMC10375586 DOI: 10.1021/acs.nanolett.3c00905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/05/2023]
Abstract
We present low-temperature magnetotransport measurements on selectively grown Sb2Te3-based topological insulator ring structures. These devices display clear Aharonov-Bohm oscillations in the conductance originating from phase-coherent transport around the ring. The temperature dependence of the oscillation amplitude indicates that the Aharonov-Bohm oscillations originate from ballistic transport along the ring arms. We attribute these oscillations to the topological surface states. Further insight into the phase coherence is gained by comparing with similar Aharonov-Bohm-type oscillations in topological insulator nanoribbons exposed to an axial magnetic field. Here, quasi-ballistic phase-coherent transport is confirmed for closed-loop topological surface states in the transverse direction enclosing the nanoribbon. In contrast, the appearance of universal conductance fluctuations indicates phase-coherent transport in the diffusive regime, which is attributed to bulk carrier transport. Thus, it appears that even in the presence of diffusive p-type charge carriers in Aharonov-Bohm ring structures, phase-coherent quasi-ballistic transport of topological surface states is maintained over long distances.
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Affiliation(s)
- Gerrit Behner
- Peter Grünberg Institut (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
- JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, Forschungszentrum Jülich and RWTH Aachen University, 52425 Jülich, Germany
| | - Abdur Rehman Jalil
- Peter Grünberg Institut (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
- JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, Forschungszentrum Jülich and RWTH Aachen University, 52425 Jülich, Germany
| | - Dennis Heffels
- Peter Grünberg Institut (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
- JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, Forschungszentrum Jülich and RWTH Aachen University, 52425 Jülich, Germany
| | - Jonas Kölzer
- Peter Grünberg Institut (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
- JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, Forschungszentrum Jülich and RWTH Aachen University, 52425 Jülich, Germany
| | - Kristof Moors
- Peter Grünberg Institut (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
- JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, Forschungszentrum Jülich and RWTH Aachen University, 52425 Jülich, Germany
| | - Jonas Mertens
- Peter Grünberg Institut (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
- JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, Forschungszentrum Jülich and RWTH Aachen University, 52425 Jülich, Germany
| | - Erik Zimmermann
- Peter Grünberg Institut (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
- JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, Forschungszentrum Jülich and RWTH Aachen University, 52425 Jülich, Germany
| | - Gregor Mussler
- Peter Grünberg Institut (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
- JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, Forschungszentrum Jülich and RWTH Aachen University, 52425 Jülich, Germany
| | - Peter Schüffelgen
- Peter Grünberg Institut (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
- JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, Forschungszentrum Jülich and RWTH Aachen University, 52425 Jülich, Germany
| | - Hans Lüth
- Peter Grünberg Institut (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
- JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, Forschungszentrum Jülich and RWTH Aachen University, 52425 Jülich, Germany
| | - Detlev Grützmacher
- Peter Grünberg Institut (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
- JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, Forschungszentrum Jülich and RWTH Aachen University, 52425 Jülich, Germany
| | - Thomas Schäpers
- Peter Grünberg Institut (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
- JARA-Fundamentals of Future Information Technology, Jülich-Aachen Research Alliance, Forschungszentrum Jülich and RWTH Aachen University, 52425 Jülich, Germany
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Rößler M, Fan D, Münning F, Legg HF, Bliesener A, Lippertz G, Uday A, Yazdanpanah R, Feng J, Taskin A, Ando Y. Top-Down Fabrication of Bulk-Insulating Topological Insulator Nanowires for Quantum Devices. NANO LETTERS 2023; 23:2846-2853. [PMID: 36976857 DOI: 10.1021/acs.nanolett.3c00169] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
In a nanowire (NW) of a three-dimensional topological insulator (TI), the quantum confinement of topological surface states leads to a peculiar sub-band structure that is useful for generating Majorana bound states. Top-down fabrication of TINWs from a high-quality thin film would be a scalable technology with great design flexibility, but there has been no report on top-down-fabricated TINWs where the chemical potential can be tuned to the charge neutrality point (CNP). Here we present a top-down fabrication process for bulk-insulating TINWs etched from high-quality (Bi1-xSbx)2Te3 thin films without degradation. We show that the chemical potential can be gate-tuned to the CNP, and the resistance of the NW presents characteristic oscillations as functions of the gate voltage and the parallel magnetic field, manifesting the TI-sub-band physics. We further demonstrate the superconducting proximity effect in these TINWs, preparing the groundwork for future devices to investigate Majorana bound states.
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Affiliation(s)
- Matthias Rößler
- University of Cologne, Physics Institute II, Zülpicher Str. 77, 50937 Köln, Germany
| | - Dingxun Fan
- University of Cologne, Physics Institute II, Zülpicher Str. 77, 50937 Köln, Germany
| | - Felix Münning
- University of Cologne, Physics Institute II, Zülpicher Str. 77, 50937 Köln, Germany
| | - Henry F Legg
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Andrea Bliesener
- University of Cologne, Physics Institute II, Zülpicher Str. 77, 50937 Köln, Germany
| | - Gertjan Lippertz
- University of Cologne, Physics Institute II, Zülpicher Str. 77, 50937 Köln, Germany
- KU Leuven, Quantum Solid State Physics, Celestijnenlaan 200 D, 3001 Leuven, Belgium
| | - Anjana Uday
- University of Cologne, Physics Institute II, Zülpicher Str. 77, 50937 Köln, Germany
| | - Roozbeh Yazdanpanah
- University of Cologne, Physics Institute II, Zülpicher Str. 77, 50937 Köln, Germany
| | - Junya Feng
- University of Cologne, Physics Institute II, Zülpicher Str. 77, 50937 Köln, Germany
| | - Alexey Taskin
- University of Cologne, Physics Institute II, Zülpicher Str. 77, 50937 Köln, Germany
| | - Yoichi Ando
- University of Cologne, Physics Institute II, Zülpicher Str. 77, 50937 Köln, Germany
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Heffels D, Burke D, Connolly MR, Schüffelgen P, Grützmacher D, Moors K. Robust and Fragile Majorana Bound States in Proximitized Topological Insulator Nanoribbons. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:723. [PMID: 36839091 PMCID: PMC9967168 DOI: 10.3390/nano13040723] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 02/02/2023] [Accepted: 02/08/2023] [Indexed: 06/18/2023]
Abstract
Topological insulator (TI) nanoribbons with proximity-induced superconductivity are a promising platform for Majorana bound states (MBSs). In this work, we consider a detailed modeling approach for a TI nanoribbon in contact with a superconductor via its top surface, which induces a superconducting gap in its surface-state spectrum. The system displays a rich phase diagram with different numbers of end-localized MBSs as a function of chemical potential and magnetic flux piercing the cross section of the ribbon. These MBSs can be robust or fragile upon consideration of electrostatic disorder. We simulate a tunneling spectroscopy setup to probe the different topological phases of top-proximitized TI nanoribbons. Our simulation results indicate that a top-proximitized TI nanoribbon is ideally suited for realizing fully gapped topological superconductivity, in particular when the Fermi level is pinned near the Dirac point. In this regime, the setup yields a single pair of MBSs, well separated at opposite ends of the proximitized ribbon, which gives rise to a robust quantized zero-bias conductance peak.
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Affiliation(s)
- Dennis Heffels
- Peter Grünberg Institute 9, Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance, 52425 Jülich, Germany
- JARA-Institute for Green IT, RWTH Aachen University, 52056 Aachen, Germany
| | - Declan Burke
- Blackett Laboratory, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Malcolm R. Connolly
- Blackett Laboratory, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Peter Schüffelgen
- Peter Grünberg Institute 9, Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance, 52425 Jülich, Germany
| | - Detlev Grützmacher
- Peter Grünberg Institute 9, Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance, 52425 Jülich, Germany
- JARA-Institute for Green IT, RWTH Aachen University, 52056 Aachen, Germany
| | - Kristof Moors
- Peter Grünberg Institute 9, Forschungszentrum Jülich & JARA Jülich-Aachen Research Alliance, 52425 Jülich, Germany
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Quantum interference probed by the thermovoltage in Sb-doped Bi 2Se 3 nanowires. iScience 2023; 26:105691. [PMID: 36713261 PMCID: PMC9881217 DOI: 10.1016/j.isci.2022.105691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 11/09/2022] [Accepted: 11/28/2022] [Indexed: 01/07/2023] Open
Abstract
The magnetic-flux-dependent dispersions of sub-bands in topologically protected surface states of a topological insulator nanowire manifest as Aharonov-Bohm oscillations (ABOs) observed in conductance measurements, reflecting the Berry's phase of π because of the spin-helical surface states. Here, we used thermoelectric measurements to probe a variation in the density of states at the Fermi level of the surface state of a topological insulator nanowire (Sb-doped Bi2Se3) under external magnetic fields and an applied gate voltage. The ABOs observed in the magnetothermovoltage showed 180° out-of-phase oscillations depending on the gate voltage values, which can be used to tune the Fermi wave number and the density of states at the Fermi level. The temperature dependence of the ABO amplitudes showed that the phase coherence was kept to T = 15 K. We suggest that thermoelectric measurements could be applied for investigating the electronic structure at the Fermi level in various quantum materials.
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Tao L, Yao B, Yue Q, Dan Z, Wen P, Yang M, Zheng Z, Luo D, Fan W, Wang X, Gao W. Vertically stacked Bi 2Se 3/MoTe 2 heterostructure with large band offsets for nanoelectronics. NANOSCALE 2021; 13:15403-15414. [PMID: 34499063 DOI: 10.1039/d1nr04281e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In recent years, two-dimensional material-based tunneling heterojunctions are emerging as a multi-functional architecture for logic circuits and photodetection owing to the flexible stacking, optical sensitivity, tunable detection band, and highly controllable conductivity behaviors. However, the existing structures are mainly focused on transition or post-transition metal chalcogenides and have been rarely investigated as topological insulator (such as Bi2Se3 or Bi2Te3)-based tunneling heterostructures. Meanwhile, it is challenging to mechanically exfoliate the topological insulator thin nanoflakes because of the strong layer-by-layer interaction with shorter interlayer spacing. Herein, we report Au-assisted exfoliation and non-destructive transfer method to fabricate large-scale Bi2Se3 thin nanosheets. Furthermore, a novel broken-gap tunneling heterostructure is designed by combing 2H-MoTe2 and Bi2Se3via the dry-transfer method. Thanks to the realized band alignment, this ambipolar-n device shows a clear rectifying behavior at Vds of 1 V. A built-in potential exceeding ∼0.7 eV is verified owing to the large band offsets by comparing the numerical solution of Poisson's equation and the experimental data. Carrier transport is governed by the majority carrier including thermionic emission and the tunneling process through the barrier height. At last, the device shows an ultralow dark current of ∼0.2 pA and a superior optoelectrical performance of Ilight/Idark ratio ≈106, a fast response time of 21 ms, and a specific detectivity of 7.2 × 1011 Jones for a visible light of 405 nm under zero-bias. Our work demonstrates a new universal method to fabricate a topological insulator and paves a new strategy for the construction of novel van der Waals tunneling structures.
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Affiliation(s)
- Lin Tao
- State Key Lab of Superhard Material, and College of Physics, Jilin University, Changchun 130012, P. R. China.
- Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), College of Physics, Jilin University, Changchun, 130012, P. R. China
| | - Bin Yao
- State Key Lab of Superhard Material, and College of Physics, Jilin University, Changchun 130012, P. R. China.
- Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), College of Physics, Jilin University, Changchun, 130012, P. R. China
| | - Qian Yue
- Institute of Semiconductors, South China Normal University, Guangzhou 510631, P. R. China.
| | - Zhiying Dan
- Institute of Semiconductors, South China Normal University, Guangzhou 510631, P. R. China.
| | - Peiting Wen
- Institute of Semiconductors, South China Normal University, Guangzhou 510631, P. R. China.
| | - Mengmeng Yang
- School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, P. R. China
| | - Zhaoqiang Zheng
- School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, P. R. China
| | - Dongxiang Luo
- Institute of Semiconductors, South China Normal University, Guangzhou 510631, P. R. China.
| | - Weijun Fan
- School of Electrical and Electronic Engineering, Nanyang Technological University, 639798, Singapore
| | - Xiaozhou Wang
- Institute of Semiconductors, South China Normal University, Guangzhou 510631, P. R. China.
| | - Wei Gao
- Institute of Semiconductors, South China Normal University, Guangzhou 510631, P. R. China.
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