Quantum transport of topological surface states in presence of circular n-p junctions

The surface states of topological insulators are characterized by spin-momentum locking, where the electron spin is locked perpendicular to its momentum. This property is preserved under gate potentials which can be used to manipulate spin currents without an external magnetic field enhancing the prospects for spintronic applications. Here, we investigate the scattering of the wave functions of topological surface states within the circular n-p junction positioned on the upper surface of the quintuple-layered three-dimensional topological insulator. With the analytical calculations we explain the scattering of these surface states in such systems.