Spectrally Programmable Spin-Polarized Photocurrents in WSe₂-NiPS₃ Magnetic van der Waals Heterostructures.

Abstract

Efficient generation and control of spin-polarized currents in semiconductors remain central challenges for spin-based electronics, particularly due to impedance mismatch and the reliance on magnetic fields or ferromagnetic contacts. Here, we introduce a materials platform for spectrally programmable spin transport based on a van der Waals (vdW) heterostructure combining the antiferromagnetic semiconductor NiPS₃ with WSe₂. In a p-n diode architecture, circularly polarized excitation produces pronounced photoconductive resonances with spin-polarization reaching 80% near the Néel temperature and persisting at ≈30% at room temperature. Remarkably, selected spectral bands retain their polarization sign across the magnetic phase transition, evidencing robust, spectrally protected spin-polarized current generation. Polarization-resolved photogalvanic measurements reveal a dominant circular injection-current mechanism, confirming spin-polarized carrier transport. First-principles calculations show that an applied electric field induces interfacial hybridization and spin-layer locking, giving rise to localized symmetry breaking and enhanced optical absorption while preserving global time-reversal symmetry. These results establish spectral tuning of excitation as a new control knob for spin transport, enabling spin-current generation without magnetic fields or polarization switching. Our findings position magnetic vdW heterostructures as a versatile platform for opto-spintronic functionality and spectrally programmable spintronic devices.