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Perpendicular andreev reflection: solid-state signature of black-hole horizon
, Article Physical Review B ; Volume 10, Issue 24 , 2019 ; 24699950 (ISSN) ; Jafari, A ; Sharif University of Technology
American Physical Society
2019
Abstract
Beenakker noticed that the peculiar band structure of Dirac fermions in two-dimensional (2D) solids allows for the specular Andreev reflection in these systems, which has no analogue in other 2D electron systems. An interesting deformation of the Dirac equation in the solid state is to tilt it, which has now been realized in materials. In this paper we report another peculiar feature of the Andreev reflection in tilted 2D Dirac cone systems. The tilt deformation of the Dirac equation is characterized by two parameters ζ=ζ(cosθ,sinθ). We show that when the tilt parameter is tuned to its "horizon value" ζ=1, irrespective of the incidence angle of electrons, the Andreev reflected hole is always...
Dirac Equation on Kerr Spacetime
, M.Sc. Thesis Sharif University of Technology ; Mashhoon, Bahram (Supervisor) ; Baghram, Shant (Supervisor)
Abstract
The physical description of particles states in the quantum theory are characterized by means of theirs mass and spin. The inertial and gravitational properties of mass are already well known in mechanics and gravitation theories as well as their quantum counterparts. In spite of mass, the inertial and gravitational properties of intrinsic spin are not studied that much.In this thesis we review the inertial and gravitational properties of intrinsic spin. Initially we explore the general procedure to formulate Dirac equation in arbitrary curved spacetime. Then we write Dirac equation in Kerr spacetime to draw physical conclusions about the interaction of Dirac particles with the Kerr...
analytical calculation of energy levels of mono- and bilayer graphene quantum dots used as light absorber in solar cells
, Article Applied Physics A: Materials Science and Processing ; Volume 122, Issue 1 , 2016 , Pages 1-8 ; 09478396 (ISSN) ; Darvish, G ; Faez, R ; Sharif University of Technology
Springer Verlag
2016
Abstract
In this paper by solving Dirac equation, we present an analytical solution to calculate energy levels and wave functions of mono- and bilayer graphene quantum dots. By supposing circular quantum dots, we solve Dirac equation and obtain energy levels and band gap with relations in a new closed and practical form. The energy levels are correlated with a radial quantum number and radius of quantum dots. In addition to monolayer quantum dots, AA- and AB-stacked bilayer quantum dots are investigated and their energy levels and band gap are calculated as well. Also, we analyze the influence of the quantum dots size on their energy spectrum. It can be observed that the band gap decreases as quantum...