Unconventional disorder effects in correlated superconductors

TL;DR

This paper investigates how strong correlations and impurity interactions uniquely affect disorder in unconventional superconductors, revealing behaviors that deviate from traditional theories and aligning with recent experimental findings.

Contribution

It introduces a new disorder paradigm considering correlations and impurity interactions, explaining unconventional effects in high-Tc superconductors beyond Abrikosov-Gor'kov theory.

Findings

Magnetic disorder can rapidly destroy high-Tc superconductivity.

Non-magnetic disorder can induce inhomogeneous magnetic phases.

Unusual disorder effects are observed in Fe-based superconductors.

Abstract

The understanding of disorder has profoundly influenced the development of condensed matter physics, explaining such fundamental effects as, for example, the transition from ballistic to diffusive propagation, and the presence of quantized steps in the quantum Hall effect. For superconductors, the response to disorder reveals crucial information about the internal gap symmetries of the condensate, and thereby the pairing mechanism itself. The destruction of superconductivity by disorder is traditionally described by Abrikosov-Gor'kov (AG) theory, which however ignores spatial modulations and ceases to be valid when impurities interfere, and interactions become important. Here we study the effects of disorder on unconventional superconductors in the presence of correlations, and explore a completely different disorder paradigm dominated by strong deviations from standard AG theory due to generation of local bound states and cooperative impurity behavior driven by Coulomb interactions. Specifically we explain under which circumstances magnetic disorder acts as a strong poison destroying high-Tc superconductivity at the sub-1% level, and when non-magnetic disorder, counter-intuitively, hardly affects the unconventional superconducting state while concomitantly inducing an inhomogeneous full-volume magnetic phase. Recent experimental studies of Fe-based superconductors have discovered that such unusual disorder behavior seem to be indeed present in those systems.