Inhomogeneous soliton ratchets under two ac forces

TL;DR

This paper investigates how two ac forces influence inhomogeneous soliton ratchets, revealing current reversals and unique behaviors due to solitons' extended nature, with potential applications in Josephson junctions.

Contribution

It extends previous soliton ratchet models to include two ac forces with non-harmonic components, analyzing their effects on current reversals and dynamics.

Findings

Current reversals depend on phase, frequency, and amplitude interplay.

Damping significantly affects soliton ratchet behavior.

Differences observed between soliton and particle ratchet phenomenology.

Abstract

We extend our previous work on soliton ratchet devices [L. Morales-Molina et al., Eur. Phys. J. B 37, 79 (2004)] to consider the joint effect of two ac forces including non-harmonic drivings, as proposed for particle ratchets by Savele'v et al. [Europhys. Lett. 67}, 179 (2004); Phys. Rev. E {\bf 70} 066109 (2004)]. Current reversals due to the interplay between the phases, frequencies and amplitudes of the harmonics are obtained. An analysis of the effect of the damping coefficient on the dynamics is presented. We show that solitons give rise to non-trivial differences in the phenomenology reported for particle systems that arise from their extended character. A comparison with soliton ratchets in homogeneous systems with biharmonic forces is also presented. This ratchet device may be an ideal candidate for Josephson junction ratchets with intrinsic large damping.