Intrinsic d-wave effects in YBa(2)Cu(3)O(7-delta) grain boundary Josephson junctions.

Area of Science:

• Superconductivity
• Materials Science
• Condensed Matter Physics

Background:

• High-temperature superconductors like Yttrium Barium Copper Oxide (YBa2Cu3O7-delta) exhibit complex electronic properties.
• Josephson junctions are crucial for understanding superconductivity and quantum effects.
• Grain boundaries in superconductors can significantly influence their critical current density.

Purpose of the Study:

• To investigate the angular dependence of Josephson critical current density (J(C)) in c-axis tilt biepitaxial grain boundary YBa2Cu3O7-delta junctions.
• To identify intrinsic d-wave pairing symmetry effects in these junctions.
• To understand how grain boundary properties affect superconducting behavior.

Main Methods:

• Fabrication of c-axis tilt biepitaxial grain boundary junctions using YBa2Cu3O7-delta.
• Measurement of the angular dependence of the Josephson critical current density (J(C)).
• Analysis of the oscillatory behavior of J(C) to determine pairing symmetry.

Main Results:

• Observed for the first time intrinsic d-wave pairing symmetry effects in YBa2Cu3O7-delta grain boundary junctions.
• Demonstrated an oscillatory dependence of J(C) on angle, characteristic of d-wave symmetry.
• Noted the presence of spontaneous currents due to faceting or impurities, yet the intrinsic d-wave effect remained evident.

Conclusions:

• The study provides direct evidence of intrinsic d-wave pairing symmetry in YBa2Cu3O7-delta grain boundary Josephson junctions.
• Angular dependence measurements are a powerful tool for probing pairing symmetry in unconventional superconductors.
• Understanding these effects is crucial for developing practical applications of high-temperature superconductors.