Signatures of two-dimensional superconductivity emerging within a three-dimensional host superconductor

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Phenomena

Background:

• Spatial disorder is known to induce a superconductor-insulator transition (SIT) in two-dimensional (2D) superconductors.
• Theoretical models predict emergent electronic granularity in materials approaching SIT, characterized by superconducting domains within an insulating matrix.

Purpose of the Study:

• To investigate the presence and characteristics of emergent electronic granularity in a three-dimensional (3D) superconductor.
• To explore the spatial electronic properties of BaPb$_{1-x}$Bi$_{x}$O$_{3}$ (BPBO) near the superconductor-insulator transition.

Main Methods:

• Spatially resolved scanning tunneling spectroscopy (STS) measurements were performed on the 3D superconductor BaPb$_{1-x}$Bi$_{x}$O$_{3}$ (BPBO).
• Analysis focused on identifying signatures of emergent electronic granularity, including superconducting domain size, energy gap distribution, and spatial correlations.

Main Results:

• The study observed three key signatures of emergent electronic granularity in BPBO, consistent with theoretical predictions for 2D systems.
• These signatures include emergent superconducting domains at the scale of the coherence length, a finite energy gap across the entire space, and enhanced spatial anticorrelation between pairing amplitude and gap magnitude.
• The findings suggest 2D superconducting behavior within a 3D host, an unexplained interdimensional phenomenon.

Conclusions:

• Emergent electronic granularity, previously thought to be a 2D phenomenon, is demonstrably present in the 3D superconductor BPBO.
• The results provide strong evidence for an interdimensional interplay of superconductivity, challenging existing theoretical frameworks.
• Further research is needed to fully understand the mechanisms behind this observed 2D-like behavior in a 3D material.