Electronic Negative Refraction across pn Junctions in Graphene

Abstract

Due to the gapless low-energy band structure carriers in graphene transform from electron-like (hole-like) to hole-like (electron-like) after passing through the gate-induced pn junction Because the momenta of these two kinds of carriers are opposite the trajectory of carriers shows a negative refraction behavior after passing through the pn junction In 2015 an experimental work reporting negative refraction in graphene was published in Nature Physics[1]; however the signal is not clear in their result This work begins with following their geometric design and parameters to check what results should be in the ideal conditions by numerical tools such as Kwant Gmsh and FEniCS A modified geometry showing much improved signals due to negative refraction is then investigated The last part of this work is devoted to a new design for a direct observation of negative refraction without the contribution from the Klein tunneling which actually dominates the signal in the previous design based on the Veselago lensing geometry

Date of Award	2020
Original language	English
Supervisor	Ming-Hao Liu (Supervisor)