Strong vortex liquid correlation from multiterminal measurements on untwinned YBa2Cu3O(7-delta) single crystals

Area of Science:

• Condensed Matter Physics
• Superconductivity
• Materials Science

Background:

• Understanding the behavior of vortex matter in high-temperature superconductors is crucial for their technological applications.
• The phase transitions in YBa2Cu3O(7--delta) single crystals, particularly the melting transition of the vortex lattice, are complex and influenced by material properties and external factors.

Purpose of the Study:

• To investigate the nature of the vortex state in untwinned YBa2Cu3O(7--delta) single crystals above the first-order melting transition.
• To explore the stability of vortex correlations under varying levels of point disorder.
• To differentiate between intervortex and intravortex correlations using various contact geometries.

Main Methods:

• Utilizing multiterminal transport measurements on untwinned YBa2Cu3O(7--delta) single crystals.
• Analyzing the behavior of the vortex liquid phase near the melting transition.
• Systematically varying weak point disorder to assess its impact on vortex correlations.
• Employing different contact geometries to probe intervortex and intravortex correlations.

Main Results:

• Evidence of a strongly correlated vortex liquid phase above the first-order melting transition was found.
• Vortex correlations demonstrated remarkable stability even with slight variations in point disorder.
• Distinct differences between intervortex and intravortex correlations were observed across different contact geometries.
• Experimental results are consistent with the local conductivity model, predicting zero resistivity along straight vortex lines.

Conclusions:

• The vortex liquid in YBa2Cu3O(7--delta) exhibits strong correlations that are robust against weak disorder.
• The local conductivity model effectively describes the observed transport properties, including zero resistivity in specific vortex configurations.
• These findings provide valuable insights into the fundamental physics of vortex matter in high-Tc superconductors.