The electronic transport properties in magnetically doped ultrathin films of topological insulators are investigated by using Landauer-Buttiker formalism. The chiral selective tunneling is addressed in such systems which leads to transport gap and as a consequence current blocking. This quantum blocking of transport occurs when the magnetic states with opposite chirality are aligned energetically. This can be observed when an electron tunnels through a barrier or well of magnetic potential induced by the exchange field. It is proved and demonstrated that this chiral transition rule fails when structural inversion asymmetric potential or an in-plane magnetization is turning on. This finding is useful to interpret quantum transport through topological-insulator thin films especially to shed light on longitudinal conductance behavior of quantum anomalous Hall effect. Besides, one can design electronic devices by means of magnetic topological-insulator thin films based on the chiral selective tunneling leading to negative differential resistance.

• Received 22 July 2017

DOI:https://doi.org/10.1103/PhysRevB.96.155440