Peak Effect in Superconductors: Melting of Larkin Domains

TL;DR

This paper investigates the peak effect in high-temperature superconductors, proposing that it results from the melting of Larkin domains rather than vortex-lattice tilt modulus effects, explaining the increase in critical current with temperature.

Contribution

It introduces a new model linking the peak effect to Larkin domain melting, challenging previous explanations based on nonlocal vortex-lattice tilt modulus.

Findings

Peak effect is associated with Larkin domain melting.

Critical current increases due to crossover from Larkin pinning length.

Model explains temperature dependence of critical current.

Abstract

Motivated by the recent observations of the peak effect in high-$T_c$ YBCO superconductors, we reexamine the origin of this unusual phenomenon. We show that the mechanism based on the $k$-dependence (nonlocality) of the vortex-lattice tilt modulus $C_{44}({\bf k})$ cannot account for the essential feature of the peak effect. We propose a scenario in which the peak effect is related to the melting of Larkin domains. In our model, the rise of critical current with increasing temperature is a result of a crossover from the Larkin pinning length to the length scale set by thermally excited free dislocations.