scholarly journals Classifying Induced Superconductivity in Atomically Thin Dirac-Cone Materials

2019 ◽  
Vol 4 (3) ◽  
pp. 83 ◽  
Author(s):  
Talantsev
Keyword(s):  
Bound States ◽  
Upper Critical Field ◽  
Critical Currents ◽  
Sample Thickness ◽  
Research Groups ◽  
Dirac Cone ◽  
Andreev Bound States ◽  
Electronic Wave Function ◽  
Out Of Plane ◽  
Previous Proposal

Recently, Kayyalha et al. (Phys. Rev. Lett., 2019, 122, 047003) reported on the anomalous enhancement of the self-field critical currents (Ic (sf, T)) at low temperatures in Nb/BiSbTeSe2-nanoribbon/Nb Josephson junctions. The enhancement was attributed to the low-energy Andreev-bound states arising from the winding of the electronic wave function around the circumference of the topological insulator BiSbTeSe2 nanoribbon. It should be noted that identical enhancement in Ic (sf, T) and in the upper critical field (Bc2 (T)) in approximately the same reduced temperatures, were reported by several research groups in atomically thin junctions based on a variety of Dirac-cone materials (DCM) earlier. The analysis shows that in all these S/DCM/S systems, the enhancement is due to a new superconducting band opening. Taking into account that several intrinsic superconductors also exhibit the effect of new superconducting band(s) opening when sample thickness becomes thinner than the out-of-plane coherence length (c (0)), we reaffirm our previous proposal that there is a new phenomenon of additional superconducting band(s) opening in atomically thin films.

scholarly journals Classifying Induced Superconductivity in Atomically Thin Dirac-Cone Materials

2019 ◽  
Author(s):  
Evgueni Talantsev
Keyword(s):  
Bound States ◽  
Upper Critical Field ◽  
Critical Currents ◽  
Sample Thickness ◽  
Research Groups ◽  
Dirac Cone ◽  
Andreev Bound States ◽  
Electronic Wave Function ◽  
Out Of Plane ◽  
Previous Proposal

Recently, Kayyalha et al. (Phys. Rev. Lett., 2019, 122, 047003) reported on anomalous enhancement of the self-field critical currents, Ic (sf,T), at low temperatures in Nb/BiSbTeSe2-nanoribbon/Nb Josephson junctions. The enhancement was attributed to the low-energy Andreev bound states arising from winding of the electronic wave function around the circumference of the topological insulator BiSbTeSe2 nanoribbon. In this paper, we show that identical enhancement in Ic(sf,T) and in the upper critical field, Bc2(T), at approximately same reduced temperatures, were reported by several research groups in atomically thin junctions based on a variety of Dirac-cone materials (DCM) earlier. Our analysis shows that in all these S/DCM/S systems the enhancement is due to a new superconducting band opening. Taking in account that several intrinsic superconductors also exhibit the effect of new superconducting band(s) opening when sample thickness becomes thinner than the out-of-plane coherence length, we strength our previous proposal that there is a new phenomenon of additional superconducting band(s) opening in atomically thin films.

scholarly journals DC Self-Field Critical Current in Superconductor/Dirac-Cone Material/Superconductor Junctions

Nanomaterials ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1554 ◽  
Author(s):  
Evgueni Talantsev
Keyword(s):  
Experimental Data ◽  
Low Temperatures ◽  
Bound States ◽  
Critical Currents ◽  
Research Groups ◽  
Dirac Cone ◽  
Data Description ◽  
Andreev Bound States ◽  
Basic Model ◽  
Electronic Wave Function

Recently, several research groups have reported on anomalous enhancement of the self-field critical currents, Ic(sf,T), at low temperatures in superconductor/Dirac-cone material/superconductor (S/DCM/S) junctions. Some papers attributed the enhancement to the low-energy Andreev bound states arising from winding of the electronic wave function around DCM. In this paper, Ic(sf,T) in S/DCM/S junctions have been analyzed by two approaches: modified Ambegaokar-Baratoff and ballistic Titov-Beenakker models. It is shown that the ballistic model, which is traditionally considered to be a basic model to describe Ic(sf,T) in S/DCM/S junctions, is an inadequate tool to analyze experimental data from these type of junctions, while Ambegaokar-Baratoff model, which is generally considered to be a model for Ic(sf,T) in superconductor/insulator/superconductor junctions, provides good experimental data description. Thus, there is a need to develop a new model for self-field critical currents in S/DCM/S systems.

scholarly journals DC Self-Field Critical Current in Superconductor/Dirac-Cone Material/Superconductor Junctions and The Request for Ballistic Model Reexamination

2019 ◽  
Author(s):  
Evgueni F. Talantsev
Keyword(s):  
Bound States ◽  
Phase Variation ◽  
Critical Currents ◽  
Dirac Cone ◽  
Conventional View ◽  
Primary Mechanism ◽  
Maximum Value ◽  
Electronic Wave Function ◽  
Superconducting Current ◽  
Ballistic Model

Recently, several research groups have reported on anomalous enhancement of the self-field critical currents, Ic(sf,T), at low temperatures in superconductor/Dirac-cone material/superconductor (S/DCM/S) junctions. Some papers attributed the enhancement to the low-energy Andreev bound states arising from winding of the electronic wave function around DCM. In this paper, Ic(sf,T) in S/DCM/S junctions have been analyzed by two approaches: modified Ambegaokar-Baratoff and ballistic Titov-Beenakker models. It is shown that the ballistic model is an inadequate tool to analyze experimental data from S/DCM/S junctions. The primary mechanism for limiting superconducting current in S/DCM/S junctions is different from the conventional view that the latter is the maximum value within the order parameter phase variation. Thus, there is a need to develop a new model for self-field critical currents in S/DCM/S systems.

scholarly journals Andreev bound states in ferromagnet-superconductor nanostructures

2003 ◽  
Vol 387 (1-2) ◽  
pp. 7-12 ◽  
Author(s):  
M. Krawiec ◽  
B.L. Györffy ◽  
J.F. Annett
Keyword(s):  
Bound States ◽  
Andreev Bound States

scholarly journals Active angular tuning and switching of Brewster quasi bound states in the continuum in magneto-optic metasurfaces

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Diego R. Abujetas ◽  
Nuno de Sousa ◽  
Antonio García-Martín ◽  
José M. Llorens ◽  
José A. Sánchez-Gil
Keyword(s):  
Magnetic Field ◽  
Magnetic Dipole ◽  
Bound States ◽  
Electromagnetic Spectrum ◽  
Resonant Modes ◽  
Out Of Plane ◽  
Q Factors ◽  
The Impact ◽  
The Continuum ◽  
Magneto Optic

Abstract Bound states in the continuum (BICs) emerge throughout physics as leaky/resonant modes that remain, however, highly localized. They have attracted much attention in photonics, and especially in metasurfaces. One of their most outstanding features is their divergent Q-factors, indeed arbitrarily large upon approaching the BIC condition (quasi-BICs). Here, we investigate how to tune quasi-BICs in magneto-optic (MO) all-dielectric metasurfaces. The impact of the applied magnetic field in the BIC parameter space is revealed for a metasurface consisting of lossless semiconductor spheres with MO response. Through our coupled electric/magnetic dipole formulation, the MO activity is found to manifest itself through the interference of the out-of-plane electric/magnetic dipole resonances with the (MO-induced) in-plane magnetic/electric dipole, leading to a rich, magnetically tuned quasi-BIC phenomenology, resembling the behavior of Brewster quasi-BICs for tilted vertical-dipole resonant metasurfaces. Such resemblance underlies our proposed design for a fast MO switch of a Brewster quasi-BIC by simply reversing the driving magnetic field. This MO-active BIC behavior is further confirmed in the optical regime for a realistic Bi:YIG nanodisk metasurface through numerical calculations. Our results present various mechanisms to magneto-optically manipulate BICs and quasi-BICs, which could be exploited throughout the electromagnetic spectrum with applications in lasing, filtering, and sensing.

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