Charge and spin transport in edge channels of a $ u=0$ quantum Hall system on the surface of topological insulators

摘要

Three-dimensional topological insulators of finite thickness can show thequantum Hall effect (QHE) at the filling factor $\nu=0$ under an externalmagnetic field if there is a finite potential difference between the top andbottom surfaces. We calculate energy spectra of surface Weyl fermions in the$\nu=0$ QHE and find that gapped edge states with helical spin structure areformed from Weyl fermions on the side surfaces under certain conditions. Theseedge channels account for the nonlocal charge transport in the $\nu=0$ QHEwhich is observed in a recent experiment on (Bi$_{1-x}$Sb$_x$)$_2$Te$_3$ films.The edge channels also support spin transport due to the spin-momentum locking.We propose an experimental setup to observe various spintronics functions suchas spin transport and spin conversion.