Sunlight Control of Ferromagnetic Damping in Photovoltaic/Ferromagnetic Heterostructures

The inexorable trend of spintronics is to develop efficient spin-control methods. For example, photovoltaic spintronics driven by sunlight has great potential in energy-saving applications. Here, a ferromagnetic/PV heterojunction is prepared on Si-substrate as Ta (4 nm)/Co (1 nm)/ZnO (from 10 to 58 nm)/PTB7-Th: PC₇₁BM/Pt (3 nm) to study how visible light affected magnetic dynamics. A linewidth variation as high as 812.55 Oe is achieved by optimizing the thickness of ZnO film used to enhance the electron transfer. Due to the photovoltaic effect, reversible ferromagnetic resonance (FMR) linewidth switches are displayed, which is attributed to the 3d orbitals occupancy of Co induced the TMS contribution and inhomogeneous broadening. This work proposes a sunlight controllable magnetic damping heterostructure for developing fast, small, energy-efficient spintronics applications.