Hydrogen-Engineered 2D Semiconductors for Reconfigurable Spintronics*

Hydrogen-functionalized two-dimensional (2D) chalcogenide-based semiconductors – Wse₂¹ and GeS² – have emerged as a promising playground for strain-tunable spintronics. At low hydrogen (H) concentrations, they exhibit robust spin polarization and display bipolar magnetic semiconducting behavior. We trace these functionalities to two synergistic mechanisms. First, site-selective H bonding is strongly dependent on lattice topology: hydrogen favors the metal site in puckered GeS, but switches preference to the chalcogen site in honeycomb WSe₂, thereby reshaping the local electronic structure. Second, hydrogen bound to low-energy Se vacancies in WSe₂ forms H vacancy complexes that introduce localized impurity states near the Fermi level and stabilize spin-polarized moments that couple efficiently with charge carriers. Once this defect-hydrogen landscape is established, biaxial strain acts as an external control knob that toggles the ground state between ferromagnetic and antiferromagnetic phases, enabling magnetoelastic switching without chemical modification. Within the broader context of layered monochalcogenides and dichalcogenides, materials renowned for their defect and strain tunability, our results position hydrogenated chalcogenide-based semiconductors as a practical platform where defect and strain engineering co-design magnetic and transport responses, opening new pathways toward low-power, reconfigurable magnetoelectronic devices.