Sharif Digital Repository

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...