Displacement Profile of Charge Density Waves and Domain Walls at Critical Depinning

TL;DR

This paper investigates how strong surface potentials affect the depinning behavior of elastic systems like charge-density waves, revealing hysteresis effects at zero temperature and velocity-dependent displacement profiles.

Contribution

It introduces a model describing the impact of surface potentials on depinning, including hysteresis phenomena and velocity effects, applicable to various physical systems.

Findings

Parabolic displacement profile when surface prevents depinning

Rhombic hysteresis curve at zero temperature

Reduction of curvature with increasing velocity

Abstract

The influence of a strong surface potential on the critical depinning of an elastic system driven in a random medium is considered. If the surface potential prevents depinning completely the elastic system shows a parabolic displacement profile. Its curvature $\mathcal{C}$ exhibits at zero temperature a pronounced rhombic hysteresis curve of width $2f_c$ with the bulk depinning threshold $f_c$. The hysteresis disappears at non-zero temperatures if the driving force is changed adiabatically. If the surface depins by the applied force or thermal creep, $\mathcal{C}$ is reduced with increasing velocity. The results apply, e.g., to driven magnetic domain walls, flux-line lattices and charge-density waves.