Single-asperity sliding friction across the superconducting phase transition

Area of Science:

• Condensed Matter Physics
• Tribology
• Materials Science

Background:

• Sliding friction involves energy dissipation through various channels like phonons, electrons, and material deformation.
• The precise contribution and coupling mechanisms of these channels, particularly electronic dissipation, remain poorly understood in many systems.

Purpose of the Study:

• To investigate the temperature-dependent friction of a single-asperity sliding on a high-temperature superconductor.
• To elucidate the role and magnitude of electronic energy dissipation in the friction of superconductors.

Main Methods:

• Performed single-asperity friction experiments on a high-temperature superconductor across a temperature range of 40-300 Kelvin.
• Modeled the observed friction behavior using a superposition of phononic and electronic friction contributions.

Main Results:

• Observed a general decrease in friction with increasing temperature, as expected.
• Identified a significant friction peak around the critical temperature (Tc).
• Found that electronic friction contributes a constant offset above Tc and vanishes below Tc following a power law consistent with Bardeen-Cooper-Schrieffer theory.

Conclusions:

• Electronic dissipation plays a significant role in the friction of high-temperature superconductors above Tc.
• Phononic and electronic friction contributions can be comparable in magnitude.
• The temperature dependence of electronic friction below Tc is well-described by superconductivity theory.