Spin Hall effect from soliton dynamics in organic polymers

Applying the extended Su–Schrieffer–Heeger model and the nonadiabatic dynamics method, the spin Hall effect (SHE) from soliton transport in two-dimensional organic ladders is investigated. An oscillating SHE is obtained by calculating the time-dependent charge and spin transfer between chains. By comparing the SHE from polaron transport, a reduced amplitude and enhanced oscillation frequency is revealed for the SHE from soliton transport. The reduction of SHE is explained by the large barrier for interchain electron transfer and the weak skew scattering off breather distortions, which originates from the strong lattice distortion of soliton as well as the large effective mass. The enhancement of oscillation behavior is investigated by spectral analysis, which is induced by the shift of a low-frequency peak to a higher onset frequency. We also calculate the field dependence of the soliton SHE under strong fields where the polaron is unstable. A field-induced increase of SHE is obtained, but the charge-spin conversion ratio decreases with field due to the acceleration of soliton. This work sheds light on the physics of organic SHE from soliton transport and clarifies the difference from polaron transport, which is helpful to further design of organic spintronic devices via carriers control.