Chirality-Tuned Spin-to-Charge Conversion in Organic Semiconductor/Ferromagnetic Bilayer

Organic semiconductors attract tremendous interest due to their flexible, large-area, low-cost optoelectronics and spintronics applications. The weak spin-orbit coupling from their light-element composition enables long-distance spin current transport but hampers spin-to-charge (StC) interconversion. Here we report a giant spin pumping effect and highly efficient StC conversion in a chiral polymer/ ferromagnetic bilayer structure. We find that the StC conversion efficiency (coherent length : λ_IEE∽0.2nm ) is orders of magnitude higher than that in conventional organic semiconductors. Furthermore, we found chiral polymers with a longer pitch exhibit a higher StC conversion efficiency, and the effects such as chirality-induced inversion symmetry and chemical bonding angles are investigated. Our work sheds novel physical insights on the spin-orbit interaction in organic spintronic devices.