Enhancing valley polarization of a MoS2 zigzag nanoribbon using double magnetic barriers

• Published in: Physica. E, Low-dimensional systems & nanostructures Low-dimensional systems & nanostructures, 2024-05, Vol.159, Article 115910
• Main Authors: Park, Daehan, Kim, Heesang, Kim, Nammee
• Format: Article
• Language: English
• Subjects: 2D material; Magnetic barrier; Nanoribbon; TMDC; Valley filter; Valley polarization; Valley Zeeman effect
• ISSN: 1386-9477; 1873-1759
• DOI: 10.1016/j.physe.2024.115910

An investigation is carried on a quantum system featuring a MoS2 zigzag nanoribbon employing double magnetic barriers. This study aims to overcome a valley polarization limitation observed in systems using a uniform magnetic field or a single magnetic barrier. A magnetic field breaks the degeneracy of the K and K′ valleys owing to the valley Zeeman effect, but reversing the direction of the magnetic field is required to invert the valley polarization. In a double magnetic barrier system, interplay between the Fano resonance (arising from the quantum interference between the continuum state of the magnetic barrier and the Landau level) and the resonant tunneling (arising from the quantum states between two barriers) indicates the potential for achieving selective spin and valley polarization by adjusting the strength and width of the magnetic barrier. This can enhance the degree of valley polarization and enable the existence of four distinct spin and valley currents. Obtaining full spin and valley polarization is shown with the optimized parameters of this system. The experimental realization of this system should enable the control of carrier valley and spin degrees of freedom in future devices. [Display omitted] •Three-band tight-binding model using three d orbitals (dx2, dx2−y2, and dz2) of Mo atoms.•Double magnetic barrier is used to enhance valley and spin polarization.•Resonant tunneling effect in the K valley and Fano resonance effect in the K′ valley.•The MoS2 zigzag nanoribbon system with double magnetic barriers along the same direction has great advantages compared with a single magnetic barrier.