The Missing Link: Magnetism and Superconductivity

TL;DR

This paper investigates the complex relationship between magnetism and superconductivity in heavy fermion compounds, revealing how local magnetic moments influence superconducting properties through optical experiments.

Contribution

It presents new experimental evidence of momentum space regions with unscreened local moments affecting superconductivity in CeTIn5 compounds.

Findings

Unscreened local moments exist in momentum space regions.

These regions influence normal and superconducting states.

Magnetism and superconductivity coexist and compete in these materials.

Abstract

The effect of magnetic moments on superconductivity has long been a controversial subject in condensed matter physics. While Matthias and collaborators experimentally demonstrated the destruction of superconductivity in La by the addition of magnetic moments (Gd), it has since been suggested that magnetic fluctuations are in fact responsible for the development of superconducting order in other systems. Currently this debate is focused on several families of unconventional superconductors including high-Tc cuprates, borocarbides as well as heavy fermion systems where magnetism and superconductivity are known to coexist. Here we report a novel aspect of competition and coexistence of these two competing orders in an interesting class of heavy fermion compounds, namely the 1-1-5 series: CeTIn5 where T=Co, Ir, or Rh. Our optical experiments indicate the existence of regions in momentum space where local moments remain unscreened. The extent of these regions in momentum space appears to control both the normal and superconducting state properties in the 1-1-5 family of heavy fermion (HF) superconductors.