Valley and spin filtering using multiple Magnetic barriers on a TMDC nanoribbon

A quantum system is investigated as a valley and spin filter using the three-band tight-binding model (TBM) and Landauer–Büttiker formalism. In a transition-metal dichalcogenide (TMDC) zigzag nanoribbon (ZNR) with multiple magnetic barriers, the valley Zeeman effect causes broken valley degeneracy of the $K$ and $K^{\prime }$ valleys in each magnetic barrier (MB) region. The energy band shifts upward for the $K^{\prime }$ valley and downward for the $K$ valley, or vice versa, depending on the direction of the magnetic field. The influence of an MB on carriers moving from the source to the drain varies depending on the valley involved. Fano resonance in the $K$ valley and resonance tunneling in the $K^{\prime }$ valley make the main contributions to valley polarization. With intrinsic spin–orbit coupling (SOC) and the ordinary Zeeman effect, the spin degeneracy of the energy bands in both valleys is broken, leading to spin polarization. Both polarizations can be enhanced by increasing either the number of MBs or the strength of the external magnetic field. With the optimized parameters of this system, it is possible to obtain currents with selective spin and valley by manipulating the incident carrier energy. An experimental implementation of this system could enable control over the carriers’ spin and valley degrees of freedom in upcoming devices.