A Pure Spin Current in Organic Materials with Ratchet Mechanism

The magnetic ratchet experiment demonstrates that directional spin diffusion can occur even in the absence of a net driving field. Inspired by these experiments, we utilize the Marcus theory to simulate spin-dependent charge hopping within a magnetic ratchet potential. Our results show that directional spin diffusion occurs only when both spatial and temporal conditions are satisfied simultaneously. Remarkably, when the system has no initial spin polarization, even pure spin current can be obtained. When combined with the spin pumping effect, it is found that the magnetic ratchet can enhance spin transport. The simulated results are in good agreement with experimental data, indicating that the magnetic ratchet effect may inherently exist in actual organic devices. Our research opens up a promising avenue for designing magnetic ratchets to achieve pure spin current and accelerate spin transport in future low-dissipation, long-distance organic spintronic devices.