Vortex dynamics in two-dimensional Josephson junction arrays with asymmetrically bimodulated potential

On the basis of resistively-shunted junction dynamics, we study vortex dynamics in two-dimensional Josephson junction arrays with asymmetrically single and bimodulated periodic pinning potential for the full range of vortex density f. The ratchet effect occurring at a certain range of temperature, current, and f, is observed in our simulation. We explain the microscopic behavior behind this effect by analyzing the vortex distribution and interaction. The reversal of the ratchet effect can be observed at several f values for a small driven current. This effect is stronger when the asymmetric potential is simultaneously introduced in two directions.

► The ratchet effect in Josephson junction arrays strongly depends on vortex density.
► The reversed ratchet effect can be observed at several f for a small current.
► The interaction between vortices can explain the reversed ratchet effect.
► The ratchet effect is enhanced by injecting the bimodulated asymmetric potential.