TUNNELING TRANSPORT IN TWO-DIMENSIONAL CONDUCTORS AND DIRAC/WEYL SEMIMETALS

Abstract

Different forms of crystal structures generally possess very different electrical, optical, and mechanical properties. During the last decade, researchers spent a considerable amount of effort in investigating Dirac semimetals with linear low energy dispersion constituted by hexagonal lattices such as graphene. Tunneling transport in such condensed matter materials constitutes the heart of novel electronic transport applications. The chiral structure of Dirac fermions allows tunneling transport between electron and hole states, which makes the Klein paradox possible in condensed matter systems. In the case of broken inversion or time reversal symmetry, an individual Dirac fermion can split into multiple Weyl fermions with different chiralities. Low crystal symmetry gives rise to a non-trivial, tilted anisotropic band structure. In this Thesis, we investigate several aspects of tunneling properties of Dirac and Weyl semimetals, which include spin and valley dependent transport as well as consequences of the tilted energy dispersion.