Spin filtering in a HgTe topological insulator PN junction via Rashba spin–orbit interaction

Abstract This work presents theoretically investigate the electron transport through a PN junction in two-dimensional topological insulator transistor made by a HgTe/CdTe quantum well with inverted-band structure. We find distinct features of the transmission by considering the Rashba spin–orbit interaction (RSOI). It’s demonstrated that the transmission can be effectively tuned by changing the incidence angle, gate voltage, Fermi energy and the RSOI modulation. By tuning the strength of RSOI modulation, the efficient spin-flip conversion for the spin-up channel and the spin-down channel are found. Furthermore, a perfect one-channel transmission mode with T = 1 is formed due to the spin-split induced by the RSOI modulation. This RSOI-induced spin-split mechanism provides us a way of pure electrical modulation to manipulate the spin and charge currents.