Isotropic Quantum Scattering and Unconventional Superconductivity

TL;DR

This paper explores how unconventional superconductivity can emerge from quantum fluctuations near a Kondo-breakdown quantum-critical point, revealing a new pairing mechanism distinct from phonon-mediated superconductivity.

Contribution

It demonstrates that local or Kondo-breakdown quantum-critical fluctuations can induce superconductivity, expanding understanding of pairing mechanisms in strongly correlated materials.

Findings

Superconductivity arises from quantum fluctuations at a Kondo-breakdown quantum-critical point.

Charge and magnetic fluctuations coexist and maximize scattering at optimal pressure.

Electrical resistivity shows sub-linear temperature dependence near the critical point.

Abstract

Superconductivity without phonons has been proposed for strongly correlated electron materials that are tuned close to a zero-temperature magnetic instability of itinerant charge carriers. Near this boundary, quantum fluctuations of magnetic degrees of freedom assume the role of phonons in conventional superconductors, creating an attractive interaction that glues electrons into superconducting pairs. Here we show that superconductivity can arise from a very different spectrum of fluctuations associated with a local or Kondo-breakdown quantum-critical point that is revealed in isotropic scattering of charge carriers and a sub-linear temperature-dependent electrical resistivity. At this critical point, accessed by applying pressure to the strongly correlated, local-moment antiferromagnet CeRhIn5, magnetic and charge fluctuations coexist and produce electronic scattering that is maximal at the optimal pressure for superconductivity. This previously unanticipated source of pairing glue opens possibilities for understanding and discovering new unconventional forms of superconductivity.