Nonadiabatic ratchet effect in superconducting films with a tilted cosine pinning potential

The influence of an ac current of arbitrary amplitude and frequency on the mixed-state dc-voltage-ac-drive ratchet response of a superconducting film with a dc current-tilted uniaxial cosine pinning potential at finite temperature is theoretically investigated. The results are obtained in the single-vortex approximation, i.e., for non-interacting vortices, with in the frame of an exact solution of the appropriate Langevin equation in terms of a matrix continued fraction. The dc voltage ratchet response is discussed as a function of ac current amplitude and frequency for various dc biases, in a wide range of corresponding dimensionless parameters. Our theoretical results are discussed in comparison with recent experimental work on the high-frequency ratchet response in nanostructured superconducting films.