Active Tuning of Light-Induced Fully Spin-Polarized Current via Inversion Symmetry Breaking

Spin-polarized photocurrent generation enables ultrafast optical manipulation and energy-efficient spin transport, offering a promising route to overcome the speed and energy limitations of conventional electronics, although suitable half-metallic materials remain exceptionally rare. Herein, we demonstrate versatile functionalities in ε-GaSe photonics by engineering vacancies to break parity-time symmetry. Previous theoretical and experimental studies highlight the exceptional performance of ε-GaSe-based photonic systems. Material-level vacancy engineering enables controlled transitions between semiconductor/metal, nonmagnetic/half-metallic, and weak/strong ferroelectric states. Device-level implementations achieve polarization switching and full conversion of charge current to a completely spin-polarized photocurrent. These findings provide critical design principles for developing tunable, energy-efficient, and multifunctional optoelectronic devices.