Saturation effects in ac+dc driven Frenkel-Kontorova model (Q2300266)

This paper deals with the study of the dynamical mode locking of different commensurate structure in the ac + dc driven Frenkel-Kontorova model with an asymmetric deformable potential. The results established in the present paper establish that when deformation gets some critical value, then there is no difference in the size of Shapiro steps and critical depinning force among different commensurate structures. Small deformation of the substrate potential introduces internal degrees of freedom into the system, and consequently, both harmonic and subharmonic Shapiro steps appear where their size is different for different commensurate structures. The authors also establish that in the presence of large deformation, the step size and the critical depinning force saturates to their values for single particles systems due to reduction of degrees of freedom. In the final section of this paper, some numerical simulations illustrate some of the abstract results of this paper.