A Quenched Disorder in the Quantum-Critical Superconductor CeCoIn₅.

Area of Science:

• Condensed Matter Physics
• Quantum Materials Science

Background:

• Emergent inhomogeneous electronic phases are key to understanding high-temperature superconductivity and novel quantum states.
• Nonmagnetic dopants in quantum-critical superconductors (QCSs) can induce spin droplets, potentially forming new magnetic states within superconducting phases.
• The precise role of nonmagnetic dopant-induced disorder in quantum-critical regimes and its relationship with superconductivity remain incompletely understood.

Purpose of the Study:

• To investigate the correlation between superconductivity and antiferromagnetism in Cd-doped CeCoIn5 under external pressure.
• To elucidate the role of quenched disorders in quantum-critical superconductors.

Main Methods:

• Measurement of current-voltage characteristics under external pressure.
• Systematic study of Cd-doped CeCoIn5, a quantum-critical superconductor.

Main Results:

• In the low-pressure regime, critical current (Ic) decreases with increasing magnetic field, typical of type-II superconductors.
• Above the critical pressure where antiferromagnetism vanishes, Ic exhibits a distinct spike near the irreversible magnetic field.
• This peak effect remains robust across the superconducting region at high pressures, indicating protected magnetic islands around dopant sites.

Conclusions:

• Quenched disorders, in the form of magnetic islands around dopant sites, are protected despite pressure-induced correlations.
• These findings offer a new perspective on the interplay between disorder, magnetism, and superconductivity in quantum-critical systems.