Direct observation of superconducting rare-region dynamics

Directly observe the dynamics of superconducting rare regions in three-dimensional and two-dimensional superconductors to clarify their role in quantum Griffiths singularities.

Background

The paper attributes the observed two-dimensional quantum Griffiths singularity in three-dimensional ZrNₓ films to quenched disorder, which produces spatially inhomogeneous superconductivity and superconducting rare regions. Near the superconductor–insulator or superconductor–metal transition, the slow dynamics of these rare regions is proposed to dominate the critical behavior.

The authors further suggest that the rare regions may possess effective two-dimensional characteristics even though the films are three-dimensional with respect to superconductivity. However, the dynamics underlying this proposed mechanism has not been directly measured, leaving experimental verification of the rare-region picture unresolved in both dimensional settings.