Superconducting properties of lithographic lead break junctions

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Superconducting materials exhibit unique quantum mechanical properties.
• Understanding the behavior of few-atom contacts is crucial for quantum electronics.
• Lead (Pb) is a well-studied superconductor with potential for novel applications.

Purpose of the Study:

• To fabricate and characterize mechanically controlled break junction samples of lead (Pb).
• To investigate the electrical and magnetic properties of few-atom lead contacts.
• To analyze the superconducting gap and tunneling spectra under varying conditions.

Main Methods:

• Electron beam lithography and physical vapor deposition for nanofabrication.
• Fabrication of mechanically controlled break junction samples.
• Electrical and magnetic property characterization in a cryostat.

Main Results:

• Demonstrated a hard superconducting gap in lead samples.
• Observed and presented tunneling spectra exhibiting a superconducting double-gap structure.
• Quantitatively described temperature and magnetic field dependence using thermal broadening and pair breaking models (Skalski model).

Conclusions:

• The fabricated lead break junctions provide a platform for studying few-atom contacts.
• The observed superconducting double-gap structure can be explained by established theoretical frameworks.
• This work contributes to the understanding of superconductivity in nanoscale systems.