Majorana modes in a topological insulator/s-wave superconductor heterostructure

In a recent experiment, signatures of Majorana fermion (MF) were found in the vortex core threading a heterostructure composed of n layers of topological insulator (TI) deposited on a bulk s-wave superconductor. Here we provide strong theoretical support to the experiment. First, we demonstrate that...

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Main Authors:	Li, Zheng-Zao, Zhang, Fu-Chun, Wang, Qiang-Hua
Format:	Online
Language:	English
Published:	Nature Publishing Group 2014
Online Access:	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4163671/

id	pubmed-4163671
recordtype	oai_dc
spelling	pubmed-41636712014-09-22 Majorana modes in a topological insulator/s-wave superconductor heterostructure Li, Zheng-Zao Zhang, Fu-Chun Wang, Qiang-Hua Article In a recent experiment, signatures of Majorana fermion (MF) were found in the vortex core threading a heterostructure composed of n layers of topological insulator (TI) deposited on a bulk s-wave superconductor. Here we provide strong theoretical support to the experiment. First, we demonstrate that MF modes appear on both top and bottom layers of TI, and are well separated for n ~ 6. The top MF becomes more extended with increasing n, in agrement with the experiment. Second, we show both analytically and numerically that right at the vortex core the MF mode is always accompanied by another low energy bound state, leading to a zero-bias peak plus a side peak in the local density of states (LDOS) therein. However, a local scalar impurity at the core can wipe out the accompanying side-peak state while leaving the zero-energy MF mode intact. Consequently the LDOS becomes symmetric about the fermi level, and the peak does not branch near the vortex core, in agreement with the experiment. Finally but unfortunately, while the MF is extremely stable against a single local impurity, the stability in terms of the critical impurity strength is reduced drastically for a moderate concentration (e.g., 10%) of impurities. Nature Publishing Group 2014-09-15 /pmc/articles/PMC4163671/ /pubmed/25219507 http://dx.doi.org/10.1038/srep06363 Text en Copyright © 2014, Macmillan Publishers Limited. All rights reserved http://creativecommons.org/licenses/by-nc-nd/4.0/ This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder in order to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/4.0/
repository_type	Open Access Journal
institution_category	Foreign Institution
institution	US National Center for Biotechnology Information
building	NCBI PubMed
collection	Online Access
language	English
format	Online
author	Li, Zheng-Zao Zhang, Fu-Chun Wang, Qiang-Hua
spellingShingle	Li, Zheng-Zao Zhang, Fu-Chun Wang, Qiang-Hua Majorana modes in a topological insulator/s-wave superconductor heterostructure
author_facet	Li, Zheng-Zao Zhang, Fu-Chun Wang, Qiang-Hua
author_sort	Li, Zheng-Zao
title	Majorana modes in a topological insulator/s-wave superconductor heterostructure
title_short	Majorana modes in a topological insulator/s-wave superconductor heterostructure
title_full	Majorana modes in a topological insulator/s-wave superconductor heterostructure
title_fullStr	Majorana modes in a topological insulator/s-wave superconductor heterostructure
title_full_unstemmed	Majorana modes in a topological insulator/s-wave superconductor heterostructure
title_sort	majorana modes in a topological insulator/s-wave superconductor heterostructure
description	In a recent experiment, signatures of Majorana fermion (MF) were found in the vortex core threading a heterostructure composed of n layers of topological insulator (TI) deposited on a bulk s-wave superconductor. Here we provide strong theoretical support to the experiment. First, we demonstrate that MF modes appear on both top and bottom layers of TI, and are well separated for n ~ 6. The top MF becomes more extended with increasing n, in agrement with the experiment. Second, we show both analytically and numerically that right at the vortex core the MF mode is always accompanied by another low energy bound state, leading to a zero-bias peak plus a side peak in the local density of states (LDOS) therein. However, a local scalar impurity at the core can wipe out the accompanying side-peak state while leaving the zero-energy MF mode intact. Consequently the LDOS becomes symmetric about the fermi level, and the peak does not branch near the vortex core, in agreement with the experiment. Finally but unfortunately, while the MF is extremely stable against a single local impurity, the stability in terms of the critical impurity strength is reduced drastically for a moderate concentration (e.g., 10%) of impurities.
publisher	Nature Publishing Group
publishDate	2014
url	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4163671/
_version_	1613133760139624448

Majorana modes in a topological insulator/s-wave superconductor heterostructure

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