2010/09/15 by Ai Yamakage, Ken‐Ichiro Imura, Ken-Ichiro Imura +3
Materials Science · Physics and Astronomy · #Charge (physics) #Condensed matter physics #Coupling (piping) #Electron #Graphene #Graphene research and applications #Lambda #Materials science #Physics #Quantum and electron transport phenomena #Quantum mechanics #Spin (aerodynamics) #Topological Materials and Phenomena #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.83.125401
published as Phys. Rev. B 83, 125401 (2011) · 14 pages, 11 figures
arxiv created 2010/09/15 · openalex publication_date 2011/03/09 · arxiv updated 2013/05/29 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The Kane-Mele model realizes a two-dimensional version of a ℤ2 topological insulator as an idealized model of graphene with intrinsic and extrinsic (Rashba) spin-orbit couplings. We study the transport of charge and spin in such a Dirac electron system in the presence of a sharp potential step, that is, a pn junction. An electron incident normal to the junction is completely reflected when Rashba coupling is dominant, whereas it is perfectly transmitted when the two types of couplings are balanced. The latter manifests in charge transport as a peak of conductance and a dip in Fano factor. Charge transport occurs in the direction normal to the barrier, whereas a spin current is induced along the barrier that is also localized in its vicinity. It is demonstrated that contributions from interband matrix elements and evanescent modes are responsible for such an interfacial spin Hall current. Our analysis of spin transport is based on the observation that in the case of vanishing Rashba coupling, each channel carries a conserved spin current, whereas only the integrated spin current is a conserved quantity in the general case. The perfect transmission/reflection of charge and conserved spin current is a consequence of reflection symmetry. Finally, we provide a quasiclassical picture of charge and spin transport by imaging flow lines over the entire sample and Veselago lensing (negative refraction).