Expansion of a superconducting vortex core into a diffusive metal

Area of Science:

• Condensed Matter Physics
• Superconductivity
• Quantum Phenomena

Background:

• Vortices in quantum condensates arise from macroscopic phase coherence.
• Understanding vortex behavior in hybrid materials is crucial for quantum technologies.

Purpose of the Study:

• To investigate the existence and properties of quantum vortices in a normal metal proximized with a superconductor.
• To characterize the structure and behavior of these vortices experimentally and theoretically.

Main Methods:

• Utilizing scanning tunneling spectroscopy (STS) to probe the electronic properties.
• Fabricating a 50 nm thick copper (Cu) layer on niobium (Nb) as the hybrid material.
• Developing a theoretical model to describe vortex evolution and properties.

Main Results:

• Observation of a proximity vortex lattice on the surface of the Cu/Nb heterostructure.
• Demonstration of regular, round vortex cores where the proximity minigap is absent.
• Vortex cores are larger than Abrikosov vortices, influenced by the effective coherence length in the proximity region.

Conclusions:

• Quantum vortices can be stabilized in relatively thick normal metal layers coupled to superconductors.
• The study provides a comprehensive theoretical framework for understanding proximity vortices.
• This research offers pathways for tuning superconducting properties in quantum hybrid systems.