Unzipping Vortices in Type-II Superconductors

TL;DR

This paper theoretically investigates the unzipping of vortex lines in type-II superconductors using magnetic-force microscopy, revealing universal properties and proposing methods to measure vortex characteristics like line tension and Luttinger liquid parameters.

Contribution

It provides a theoretical framework for understanding vortex unzipping transitions and introduces experimental techniques to measure vortex properties in superconductors.

Findings

Universal unzipping transition depends on defect dimensionality.

Unzipping from a plane with many vortices is sensitive to vortex interactions.

Proposes a method to measure vortex line tension directly.

Abstract

The unzipping of vortex lines using magnetic-force microscopy from extended defects is studied theoretically. We study both the unzipping isolated vortex from common defects, such as columnar pins and twin-planes, and the unzipping of a vortex from a plane in the presence of other vortices. We show, using analytic and numerical methods, that the universal properties of the unzipping transition of a single vortex depend only on the dimensionality of the defect in the presence and absence of disorder. For the unzipping of a vortex from a plane populated with many vortices is shown to be very sensitive to the properties of the vortices in the two-dimensional plane. In particular such unzipping experiments can be used to measure the ``Luttinger liquid parameter'' of the vortices in the plane. In addition we suggest a method for measuring the line tension of the vortex directly using the experiments.