Influence of the velocity barrier on the massive Dirac electron transport in a monolayer MoS2 quantum structure

Using the transfer matrix method,spin-and valley-dependent electron transport properties modulated by the velocity barrier were studied in the normal/ferromagnetic/normal monolayer MoS2 quantum structure.Based on Snell’s Law in optics,we define the velocity barrier asξ=v2/v1 by changing the Fermi velocity of the intermediate ferromagnetic region to obtain a deflection condition during the electron transport process in the structure.The results show that both the magnitude and the direction of spin-and valley-dependent electron polarization can be regulated by the velocity barrier.−100%polarization of spin-and valley-dependent electron can be achieved forξ>1,while 100%polarization can be obtained forξ<1.Furthermore,it is determined that perfect spin and valley transport always occur at a large incident angle.In addition,the spin-and valley-dependent electron transport considerably depends on the length kFL and the gate voltage U(x)of the intermediate ferromagnetic region.These findings provide an effective method for designing novel spin and valley electronic devices.