Little-Parks Effect Governed by Magnetic Nanostructures with Out-of-Plane Magnetization Little-Parks Effect Governed by Magnetic Nanostructures with Out-of-Plane Magnetization

TL;DR

This study demonstrates that magnetic nanostructures with out-of-plane magnetization can enhance and control the Little-Parks effect in superconductors by inducing vortex-antivortex pairs through stray magnetic fields.

Contribution

It reveals how magnetic nanodots with perpendicular magnetization influence the Little-Parks effect, introducing a new way to manipulate superconducting properties via magnetic nanostructures.

Findings

Magnetic nanodots generate stray fields that induce vortex-antivortex pairs.

The Little-Parks oscillations are enhanced by magnetic nanostructures.

Comparison shows increased effect with larger effective nanodot size.

Abstract

Little-Parks effect names the oscillations in the superconducting critical temperature as a function of the magnetic field. This effect is related to the geometry of the sample. In this work, we show that this effect can be enhanced and manipulated by the inclusion of magnetic nanostructures with perpendicular magnetization. These magnetic nanodots generate stray fields with enough strength to produce superconducting vortex-antivortex pairs. So that, the L-P effect deviation from the usual geometrical constrictions is due to the interplay between local magnetic stray fields and superconducting vortices. Moreover, we compare our results with a low-stray field sample (i.e. with the dots in magnetic vortex state) showing how the enhancement of the L-P effect can be explained by an increment of the effective size of the nanodots.