Current-dependent crossover in the flux dynamics of thin films

S. L. Prischepa; M. Salvato; L. Maritato

doi:10.1209/epl/i2003-10123-2

All issues

Volume 65 / No 4 (February 2004)

Europhys. Lett., 65 4 (2004) 540-545

Abstract

Issue		Europhys. Lett. Volume 65, Number 4, February 2004


Page(s)		540 - 545
Section		Condensed matter: electronic structure, electrical, magnetic, and optical properties
DOI		https://doi.org/10.1209/epl/i2003-10123-2
Published online		01 February 2004

Europhys. Lett., 65 (4), pp. 540-545 (2004)

Current-dependent crossover in the flux dynamics of $\chem{MgB_2}$ thin films

S. L. Prischepa, M. Salvato and L. Maritato

Dipartimento di Fisica “E. R. Caianiello”, Università di Salerno and INFM/Coherentia - Via S. Allende, I-84081 Baronissi (SA), Italy

Received: 19 June 2003
Accepted: 10 December 2003

Abstract

We have investigated the dissipative behaviour of $\chem{MgB_2}$ textured thin films at different perpendicular magnetic fields H and bias currents J, to study activation energy dependencies $U(J)$ and $U(H)$ . For $J<J^*$ , where J^* is a magnetic-field–dependent crossover current, activation energies are weakly current dependent, $U(J)\approx$ const, while, for $J>J^*$ , $U(J)\sim-\ln J$ . At $J<J^*$ , the magnetic-energy dependencies are logarithmic, $U(H)\sim-\ln H$ , while for $J>J^*$ , $U(H)\sim H^{-1}$ , up to $\mu_0H\approx 5$ $\un{T}$ . The $J^*(H)$ curve separates two zones with different vortex dynamics. We discuss the curve in terms of a current-driven transition from a thermally activated flux flow to a flux creep regime. For pronounced disorder, the data suggest the influence of the activation energy distribution on the $U(J)$ and $U(H)$ dependencies.

PACS: 74.78.-w – Superconducting films and low-dimensional structures

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.