Non-Hermitian indirect exchange interaction in a topological insulator coupled to a ferromagnetic metal

Abstract We theoretically demonstrate non-Hermitian indirect interaction between two magnetic impurities placed at the interface between a 3D topological insulator and a ferromagnetic metal. The coupling of topological insulator and the ferromagnet introduces not only Zeeman exchange field on the su...

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Autores principales:	Mir Vahid Hosseini, Mehdi Askari
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/e5ef98b956124df6a0094297cf5c3d3a
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spelling	oai:doaj.org-article:e5ef98b956124df6a0094297cf5c3d3a2021-11-14T12:18:15ZNon-Hermitian indirect exchange interaction in a topological insulator coupled to a ferromagnetic metal10.1038/s41598-021-01591-x2045-2322https://doaj.org/article/e5ef98b956124df6a0094297cf5c3d3a2021-11-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-01591-xhttps://doaj.org/toc/2045-2322Abstract We theoretically demonstrate non-Hermitian indirect interaction between two magnetic impurities placed at the interface between a 3D topological insulator and a ferromagnetic metal. The coupling of topological insulator and the ferromagnet introduces not only Zeeman exchange field on the surface states but also broadening to transfer the charge and spin between the surface states of the topological insulator and the metallic states of the ferromagnet. While the former provides bandgap at the charge neutrality point, the latter causes non-Hermiticity. Using the Green’s function method, we calculate the range functions of magnetic impurity interactions. We show that the charge decay rate provides a coupling between evanescent modes near the bandgap and traveling modes near the band edge. However, the spin decay rate induces a stronger coupling than the charge decay rate so that higher energy traveling modes can be coupled to lower energy evanescent ones. This results in a non-monotonic behavior of the range functions in terms of distance and decay rates in the subgap regime. In the over gap regime, depending on the type of decay rate and on the distance, the amplitude of spatial oscillations would be damped or promoted.Mir Vahid HosseiniMehdi AskariNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-15 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Mir Vahid Hosseini Mehdi Askari Non-Hermitian indirect exchange interaction in a topological insulator coupled to a ferromagnetic metal
description	Abstract We theoretically demonstrate non-Hermitian indirect interaction between two magnetic impurities placed at the interface between a 3D topological insulator and a ferromagnetic metal. The coupling of topological insulator and the ferromagnet introduces not only Zeeman exchange field on the surface states but also broadening to transfer the charge and spin between the surface states of the topological insulator and the metallic states of the ferromagnet. While the former provides bandgap at the charge neutrality point, the latter causes non-Hermiticity. Using the Green’s function method, we calculate the range functions of magnetic impurity interactions. We show that the charge decay rate provides a coupling between evanescent modes near the bandgap and traveling modes near the band edge. However, the spin decay rate induces a stronger coupling than the charge decay rate so that higher energy traveling modes can be coupled to lower energy evanescent ones. This results in a non-monotonic behavior of the range functions in terms of distance and decay rates in the subgap regime. In the over gap regime, depending on the type of decay rate and on the distance, the amplitude of spatial oscillations would be damped or promoted.
format	article
author	Mir Vahid Hosseini Mehdi Askari
author_facet	Mir Vahid Hosseini Mehdi Askari
author_sort	Mir Vahid Hosseini
title	Non-Hermitian indirect exchange interaction in a topological insulator coupled to a ferromagnetic metal
title_short	Non-Hermitian indirect exchange interaction in a topological insulator coupled to a ferromagnetic metal
title_full	Non-Hermitian indirect exchange interaction in a topological insulator coupled to a ferromagnetic metal
title_fullStr	Non-Hermitian indirect exchange interaction in a topological insulator coupled to a ferromagnetic metal
title_full_unstemmed	Non-Hermitian indirect exchange interaction in a topological insulator coupled to a ferromagnetic metal
title_sort	non-hermitian indirect exchange interaction in a topological insulator coupled to a ferromagnetic metal
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/e5ef98b956124df6a0094297cf5c3d3a
work_keys_str_mv	AT mirvahidhosseini nonhermitianindirectexchangeinteractioninatopologicalinsulatorcoupledtoaferromagneticmetal AT mehdiaskari nonhermitianindirectexchangeinteractioninatopologicalinsulatorcoupledtoaferromagneticmetal
_version_	1718429321267249152

Non-Hermitian indirect exchange interaction in a topological insulator coupled to a ferromagnetic metal

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