High-T_cCooper-pair injection in a semiconductor-superconductor structure

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Optics

Background:

• Superconducting proximity effects are crucial for advanced electronic devices.
• High-temperature superconductors (HTS) offer unique advantages for integration with semiconductors.
• Demonstrating Andreev reflection in HTS/semiconductor junctions is a significant challenge.

Purpose of the Study:

• To investigate Andreev reflection in Yttrium Barium Copper Oxide (YBCO)/Gallium Nitride (GaN) junctions.
• To assess the feasibility of superconducting proximity in HTS/semiconductor heterostructures.
• To explore potential applications in novel optoelectronics and quantum optics.

Main Methods:

• Differential conductance spectroscopy was employed to probe the YBCO-GaN junction.
• Experimental data was compared with a theoretical model for validation.
• Measurements were conducted up to the critical temperature of the superconductor.

Main Results:

• A distinct zero-bias peak, characteristic of Andreev reflection, was observed.
• This peak persisted up to the critical temperature, indicating robust superconducting properties.
• A small superconducting order parameter (Δ ∼ 1 meV) was determined for the junction.

Conclusions:

• The study successfully demonstrated Andreev reflection in a YBCO-GaN junction.
• This finding represents a milestone towards realizing superconducting proximity in HTS/semiconductor systems.
• Efficient Cooper pair injection opens possibilities for advanced optoelectronic and quantum optical applications.