scholarly journals Nearly flat Andreev bound states in superconductor-topological insulator hybrid structures

2012 ◽  
Vol 86 (16) ◽  
Author(s):  
Mahmoud Lababidi ◽  
Erhai Zhao
Keyword(s):  
Topological Insulator ◽  
Bound States ◽  
Hybrid Structures ◽  
Andreev Bound States

Suppressed Andreev reflection and helical Andreev bound states in triplet superconductor three-dimensional topological insulator

2015 ◽  
Vol 29 (04) ◽  
pp. 1550018 ◽  
Author(s):  
M. Khezerlou ◽  
H. Goudarzi
Keyword(s):  
Topological Insulator ◽  
Bound States ◽  
Andreev Reflection ◽  
Chemical Potential ◽  
Three Dimensional ◽  
P Wave ◽  
Superconducting Gap ◽  
Tunneling Conductance ◽  
Andreev Bound States ◽  
Josephson Supercurrent

Effect of proximity-induced unconventional p-wave superconductivity in a three-dimensional topological insulator-based S/F/S structure on the Andreev bound states (ABSs) and Josephson supercurrent is studied. We investigate, in detail, the suppression of Andreev reflection and helical ABSs in the presence of three types of triplet superconducting gap. The magnetization of ferromagnetic section is perpendicular to the surface of junction. The influence of such features on the supercurrent flow on the surface of the topological insulator is studied. We carry out our goal by introducing a relevant form of Dirac spinors for gapless renormalized by chemical potential μ excitation states. Therefore, it enables us to consider the virtual Andreev process, simultaneously, and we propose to investigate it in a tunneling conductance junction. It is shown that the results obtained in this case are completely different from those in conventional superconductivity, as s- or d-waves, for example, the magnetization is found to decrease the gap for px and px+ipy case, whereas increase it for py order. Strongly suppressed Andreev reflection is demonstrated.

scholarly journals Study on Green’s function on topological insulator surface

2018 ◽  
Vol 376 (2125) ◽  
pp. 20150246 ◽  
Author(s):  
Bo Lu ◽  
Yukio Tanaka
Keyword(s):  
Green’S Function ◽  
Density Of States ◽  
Green's Function ◽  
Topological Insulator ◽  
Bound States ◽  
Local Density ◽  
Josephson Current ◽  
Majorana Fermion ◽  
Local Density Of States ◽  
Andreev Bound States

In the theory of superconducting junctions, Green’s function has an important role for obtaining Andreev bound states, local density of states and Josephson current in a systematic way. In this article, we show how to construct Green’s function on the surface of a topological insulator following McMillan’s formalism where the energy spectrum of electrons obeys a linear dispersion. For a model of a superconductor (S)/ferromagnet (F)/normal metal (N) junction, we show that the generation of a Majorana fermion gives rise to the enhanced local density of states and pair amplitude of odd-frequency pairing. We also derive an extended Furusaki–Tsukada’s formula of DC Josephson current in S/F/S junctions. The obtained Josephson current depends on the direction and magnitude of the magnetization. This article is part of the theme issue ‘Andreev bound states’.

scholarly journals Andreev bound states at spin-active interfaces

2018 ◽  
Vol 376 (2125) ◽  
pp. 20150002
Author(s):  
D. Beckmann ◽  
F. Hübler ◽  
M. J. Wolf ◽  
H. v. Löhneysen
Keyword(s):  
Bound States ◽  
Hybrid Structures ◽  
Cooper Pairs ◽  
Important Ingredient ◽  
Theme Issue ◽  
Andreev Bound States ◽  
Interface Scattering ◽  
Spin Dependent Scattering ◽  
Parameter Symmetry ◽  
Order Parameter Symmetry

Andreev bound states are ubiquitous in superconducting hybrid structures. They are formed near impurities, in Josephson junctions, in vortex cores and at interfaces. At spin-active superconductor–ferromagnet interfaces, Andreev bound states are formed due to spin-dependent scattering phases. Spin-dependent phase shifts are an important ingredient for the generation of triplet Cooper pairs in superconductor–ferromagnet hybrid structures. Spectroscopy of Andreev bound states is a powerful probe of superconducting order parameter symmetry, as well as spin-dependent interface scattering and the triplet proximity effect. This article is part of the theme issue ‘Andreev bound states’.

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