Andreev Reflection and Klein Tunneling in High-Temperature Superconductor-Graphene Junctions

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• Quantum materials exhibit resonances in electronic transport, typically from single scattering events.
• Understanding complex scattering mechanisms is key to developing novel electronic devices.

Purpose of the Study:

• To investigate the emergence of resonances from combined scattering mechanisms in graphene-superconductor heterojunctions.
• To explore the interplay between superconductivity and graphene p-n junctions in electronic transport.

Main Methods:

• Fabrication of graphene-high-temperature superconductor heterojunctions using Bi_{2}Sr_{2}Ca_{1}Cu_{2}O_{8+δ}.
• Experimental measurements of electronic transport under varying gating conditions.
• Quantum transport calculations to model the observed phenomena.

Main Results:

• Observed novel resonances resulting from the simultaneous action of superconductivity and graphene p-n junction scattering.
• Demonstrated that these resonances originate from Andreev reflection and Klein tunneling at graphene interfaces.
• Confirmed the persistence of resonances across p^{+}-p and p-n gating configurations.
• Identified suppression of oscillation amplitude related to Andreev reflection and the superconducting gap.

Conclusions:

• A hybrid scattering mechanism involving superconductivity and graphene p-n junctions has been identified.
• This finding offers new insights into quantum transport in graphene-superconductor systems.
• The results have significant implications for the development of graphene-based Josephson junctions.