Veselago focusing of anisotropic massless Dirac fermions.
The massless Dirac fermions (MDF) emerge as the quasiparticles in various novel materials such as graphene and topological insulators, and exhibit a lot of intriguing properties in which the Veselago focusing is an outstanding example and has a lot of possible applications. However, the Veselago focusing merely occurs in the p-n junction based on the isotropic MDF, and lacks the tunability for the realistic applications. Here, motivated by the continuing emergence of Dirac materials, we investigate the propagation behaviors of anisotropic MDF in the p-n junction structure. By projecting the Hamiltonian of the anisotropic MDF to that of the isotropic MDF and deriving the exact analytical expression of the propagator, the precise Veselago focusing is demonstrated without demanding the mirror symmetry for an electron source and its focusing image, whose highly tunable features bring us to propose the device to probe the masked atom-scale defects. This study provides an innovative concept to realize the Veselago focusing and is relevant to its potential applications, and opens a venue to design the electron optics devices by exploiting the anisotropic MDF.
Publisher URL: http://arxiv.org/abs/1801.09364