Quantum Griffiths Singularity in Ordered Artificial Superconducting-Islands-Array on Graphene

Area of Science:

• Condensed Matter Physics
• Quantum Materials
• Superconductivity

Background:

• The Quantum Griffiths phase (QGP) describes quantum phase transitions in 2D superconductors.
• The Quantum Griffiths singularity (QGS) theoretically predicts inhomogeneous superconducting rare regions.
• Experimental verification of these rare regions remains a challenge.

Purpose of the Study:

• To experimentally demonstrate the Quantum Griffiths singularity (QGS) in an artificial system.
• To provide visual evidence for the emergence of superconducting rare regions.
• To explore the universal features of QGP in heterostructured systems.

Main Methods:

• Fabrication of an artificial ordered superconducting-islands-array on monolayer graphene using an anodic aluminum oxide (AAO) membrane.
• Investigation of QGS under both in-plane and out-of-plane magnetic fields.
• Analysis of the dynamical critical exponent and activated scaling behavior.

Main Results:

• Experimental evidence for QGS in the artificial graphene system.
• Observation of direct activated scaling behavior.
• Phase diagram confirms QGP emergence in rare superconducting regions with vanished quantum coherence.

Conclusions:

• The study provides the first intuitive experimental verification of superconducting rare regions.
• It demonstrates universal features of QGP in artificial heterostructures.
• Offers a visualized platform for theoretical QGS proposals.