Geometry-controlled spin filtering in MoS2 nanoribbon junctions

Controlling spin polarization with simple and scalable methods is essential for advancing spintronic devices. Conventional approaches often rely on strong fields or complex heterostructures, limiting practical implementation. Here, we demonstrate geometry-controlled spin filtering in an H-shaped MoS2 nanoribbon junction, where alternating zigzag and armchair edges form a double-barrier potential for edge states. This structure confines quantized subbands that enable spin-dependent resonant tunneling under a low exchange field. The resulting transmission exhibits distinct spin-split resonant peaks and oscillatory spin polarization for both electrons and holes. Spin polarization is robust to variations in the armchair edge width but is sensitive to zigzag-edge modulation due to its impact on quantum confinement. Enhanced spin filtering emerges with increased exchange field strength. This work offers a geometry-driven approach for efficient spin manipulation in two-dimensional nanoribbon systems.