Crossovers Between Elastic, Plastic and Quantum Creep in Two Dimensional YBa_2Cu_3O_7/PrBa_2Cu_3O_7 Superlattices

TL;DR

This study investigates 2D vortex dynamics in YBa_2Cu_3O_7/PrBa_2Cu_3O_7 superlattices, revealing crossover behaviors among elastic, plastic, and quantum creep, and challenging the existence of a 2D vortex glass at all temperatures.

Contribution

It provides new insights into vortex creep mechanisms and demonstrates the interplay of elastic, plastic, and quantum effects in 2D vortex systems.

Findings

Observation of 2D collective creep with specific activation energy.

Identification of vortex melting due to dislocation dynamics.

Evidence of quantum tunneling affecting resistive transition plateau.

Abstract

Two-dimensional(2D) vortex dynamics was studied in an YBa_2Cu_3O_7/ PrBa_2Cu_3O_7 superlattice by measuring the I-V characteristics. In the high current limit, 2D collective creep was observed with an activation energy characterized by U(j)=a j^u. A dislocation mediated vortex melting happened when the temperature increased. In the low current limit, the exponential growth of energy barrier for elastic motion was prohibited by the plastic deformation of vortices. A plateau in the resistive transition was observed, which was attributed to possible quantum tunneling of vortices. Our results suggest that a 2D vortex glass can not exist at any temperature, including T=0 K.