A peak in the critical current for quantum critical superconductors

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Critical current (I_c) studies are vital for practical superconductor applications, defining the zero-resistance current limit.
• Understanding the interplay between superconductivity and magnetic order is crucial in strongly correlated materials.

Purpose of the Study:

• To investigate the pressure dependence of the zero-field critical current (I_c(0)) in CeRhIn₅ and its Sn-doped variant.
• To identify the relationship between a hidden quantum critical point (QCP) and unconventional superconductivity.

Main Methods:

• Measurements of critical current (I_c) and DC conductivity (σ_dc) under varying pressure.
• Analysis of the pressure dependence of superconducting properties in CeRhIn₅-based compounds.

Main Results:

• A distinct peak in the zero-field critical current (I_c(0)) was observed at a pressure-induced quantum critical point (QCP).
• The critical current's pressure dependence showed universal behavior, driven by QCP-associated critical fluctuations.
• DC conductivity exhibited a minimum at the QCP, anti-correlated with the critical current peak.

Conclusions:

• The zero-field critical current serves as a sensitive probe for uncovering hidden quantum critical points within superconducting phases.
• This work establishes a direct correlation between quantum critical points and the emergence of unconventional superconductivity in strongly correlated systems.