Crossover between channeling and pinning at twin boundaries in YBa2Cu3O7 thin films

Area of Science:

• Superconductivity
• Materials Science
• Condensed Matter Physics

Background:

• High-temperature superconductors like YBa2Cu3O7 (YBCO) exhibit complex behaviors under magnetic fields.
• Understanding vortex dynamics and pinning mechanisms is crucial for optimizing superconducting properties.

Purpose of the Study:

• To investigate the influence of twin boundaries (TBs) on the critical current (Jc) of YBCO films.
• To elucidate the mechanisms governing vortex interactions with TBs across various temperatures, magnetic fields, and angles.

Main Methods:

• Experimental measurement of critical current density (Jc) in YBCO films.
• Systematic variation of temperature, magnetic field strength, and field angle relative to TBs.
• Quantitative modeling of observed phenomena, including flux-cutting-mediated vortex channeling.

Main Results:

• A significant suppression of Jc was observed when magnetic fields were aligned with TB directions, attributed to vortex channeling.
• A crossover to a regime where TBs act as planar pinning centers, enhancing Jc, was identified under specific conditions.
• Intrinsic pinning along TBs was found to be comparable to pinning between TBs in this enhanced Jc regime.

Conclusions:

• Twin boundaries in YBCO films exhibit dual behavior, acting as channels for vortex penetration or as effective pinning sites.
• The interplay between vortex channeling and planar pinning at TBs dictates the overall Jc, offering insights into superconductor design.
• Controlling TB interactions is key to maximizing the performance of YBCO superconducting films.