Nonequilibrium structures and dynamic transitions in driven vortex lattices with disorder

TL;DR

This paper reviews studies on driven vortex lattices with disorder, revealing two dynamical phase transitions characterized by changes in flow behavior, noise, and effective temperature, with implications for understanding vortex dynamics in superconductors.

Contribution

It identifies and characterizes two distinct dynamical phase transitions in driven vortex lattices with disorder, including the transition to a frozen transverse solid and the behavior of effective temperature.

Findings

Transition from plastic to smectic flow at Fp

Sharp transition to frozen transverse solid at Ft

Effective transverse temperature decreases with driving force

Abstract

We review our studies of elastic lattices driven by an external force $F$ in the presence of random disorder, which correspond to the case of vortices in superconducting thin films driven by external currents. Above a critical force $F_c$ we find two dynamical phase transitions at $F_p$ and $F_t$, with $F_c<F_p<F_t$. At $F_p$ there is a transition from plastic flow to smectic flow where the noise is isotropic and there is a peak in the differential resistance. At $F_t$ there is a sharp transition to a frozen transverse solid where both the transverse noise and the diffussion fall down abruptly and therefore the vortex motion is localized in the transverse direction. From a generalized fluctuation-dissipation relation we calculate an effective transverse temperature in the fluid moving phases. We find that the effective temperature decreases with increasing driving force and becomes equal to the equilibrium melting temperature when the dynamic transverse freezing occurs.