Little-Parks effect governed by magnetic nanostructures with out-of-plane magnetization

Area of Science:

• Condensed Matter Physics
• Materials Science

Background:

• The Little-Parks effect describes oscillations in superconducting critical temperature with applied magnetic field.
• This phenomenon is intrinsically linked to sample geometry and topology.

Purpose of the Study:

• To investigate the enhancement and manipulation of the Little-Parks effect using magnetic nanostructures.
• To understand the role of local magnetic stray fields and superconducting vortices in modifying the Little-Parks effect.

Main Methods:

• Fabrication and characterization of superconducting samples integrated with magnetic nanodots.
• Measurement of superconducting critical temperature as a function of magnetic field.
• Comparison between samples with high-stray field nanodots and low-stray field (vortex state) nanodots.

Main Results:

• Magnetic nanostructures with perpendicular magnetization significantly enhance the Little-Parks effect.
• The presence of nanodots generates stray fields capable of producing superconducting vortex-antivortex pairs.
• The deviation from standard geometric effects is attributed to the interplay of local stray fields and superconducting vortices.

Conclusions:

• The Little-Parks effect can be actively controlled and amplified through engineered magnetic nanostructures.
• The observed enhancement is linked to the increased effective size of nanodots due to their stray fields, leading to vortex-antivortex pair formation.