Unzipping flux lines from extended defects in type-II superconductors

¹ Department of Physics, Harvard University - Cambridge, MA 02138, USA
² Physicochimie Curie (CNRS-UMR168), Institut Curie, Section de Recherche 26 rue d'Ulm, 75248 Paris Cedex 05, France
³ Department of Physics, Technion - Haifa 32000, Israel
⁴ Department of Physics, Boston University - Boston, MA 02215, USA

Received: 5 October 2005
Accepted: 25 November 2005

Abstract

With magnetic force microscopy in mind, we study the unbinding transition of individual flux lines from extended defects like columnar pins and twin planes in type-II superconductors. In the presence of point disorder, the transition is universal with an exponent which depends only on the dimensionality of the extended defect. We also consider the unbinding transition of a single vortex line from a twin plane occupied by other vortices. We show that the critical properties of this transition depend strongly on the Luttinger liquid parameter which describes the long-distance physics of the two-dimensional flux line array.