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 Switchable Purcell enhancement of photoluminescence by GST film

2021 ◽  
Vol 2015 (1) ◽  
pp. 012077
Author(s):  
O M Kushchenko ◽  
A D Sinelnik ◽  
I I Shishkin ◽  
D S Gets ◽  
S V Makarov ◽  
...  
Keyword(s):  
Green’S Function ◽  
Density Of States ◽  
Green's Function ◽  
Local Density ◽  
Angular Spectrum ◽  
Local Density Of States ◽  
Purcell Factor ◽  
Dyadic Green’S Function ◽  
Dyadic Green's Function ◽  
Radiation Enhancement

Abstract In the present paper perovskite radiation enhancement on crystalline GST film compared to amorphous one has been studied. The photonic local density of states has been calculated by angular spectrum representation of the dyadic Green’s function. The Purcell factor has been calculated for perovskite luminescent on both amorphous and crystalline GST film. Almost 80% enhancement has been observed at wavelength 950 nm for system with perovskite thickness 25 nm, GST thickness 110 nm.

scholarly journals Near-Field Excitation of Bound States in the Continuum in All-Dielectric Metasurfaces through a Coupled Electric/Magnetic Dipole Model

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 998
Author(s):  
Diego R. Abujetas ◽  
José A. Sánchez-Gil
Keyword(s):  
Magnetic Dipole ◽  
Density Of States ◽  
Bound States ◽  
Local Density ◽  
Near Field ◽  
Field Pattern ◽  
Local Density Of States ◽  
Optical Modes ◽  
Source Excitation ◽  
The Continuum

Resonant optical modes arising in all-dielectric metasurfaces have attracted much attention in recent years, especially when so-called bound states in the continuum (BICs) with diverging lifetimes are supported. With the aim of studying theoretically the emergence of BICs, we extend a coupled electric and magnetic dipole analytical formulation to deal with the proper metasurface Green function for the infinite lattice. Thereby, we show how to excite metasurface BICs, being able to address their near-field pattern through point-source excitation and their local density of states. We apply this formulation to fully characterize symmetry-protected BICs arising in all-dielectric metasurfaces made of Si nanospheres, revealing their near-field pattern and local density of states, and, thus, the mechanisms precluding their radiation into the continuum. This formulation provides, in turn, an insightful and fast tool to characterize BICs (and any other leaky/guided mode) near fields in all-dielectric (and also plasmonic) metasurfaces, which might be especially useful for the design of planar nanophotonic devices based on such resonant modes.

Real-space Green's-function approach within RHEED

1999 ◽  
Vol 55 (2) ◽  
pp. 133-142
Author(s):  
P. M. Derlet ◽  
A. E. Smith
Keyword(s):  
Green’S Function ◽  
Density Of States ◽  
Green's Function ◽  
Local Density ◽  
Perturbation Expansion ◽  
Surface Region ◽  
High Energy ◽  
Real Space ◽  
Resonance Phenomenon ◽  
Total Density

Green's-function techniques are used to obtain a real-space series solution for the elastic reflection high-energy electron diffraction (RHEED) from a crystalline surface. A renormalized perturbation expansion due to potential self-scattering is developed for the local real-space Green's function. With the Pt (111) surface as an example, numerical results are obtained for reflection coefficients and intensities. In particular, calculations are performed to obtain the local density of states at and near the surface region. Total density-of-states calculations are also performed. These provide a basis for a discussion of the form of resonant electronic Green's functions that can be used to describe the surface resonance phenomenon within RHEED.

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