Superconductivity in Actinide Materials

TL;DR

This paper discusses the complex electronic behaviors of actinide materials, especially Pu-based superconductors like PuCoGa5, highlighting their unconventional superconductivity linked to magnetic fluctuations rather than phonons.

Contribution

It provides new insights into the nature of 5f electrons in actinide superconductors, challenging phonon-mediated theories and drawing parallels with other correlated electron systems.

Findings

PuCoGa5 has a high Tc of 18.5 K, unusual for actinides.

Superconductivity in PuCoGa5 is likely due to antiferromagnetic fluctuations.

Similarities with cuprates suggest new perspectives on 5f electron behavior.

Abstract

Actinide materials play a special role in condensed matter physics, spanning behaviours of itinerant d-electron and localized 4f-electron materials. An intermediate state, found notably in Pu-based materials whose 5f electrons are neither fully localized nor itinerant, is particularly challenging to understand. Superconductivity appearing in some actinide materials provides clues to the nature of the 5f electrons. PuCoGa5, the first Pu-based superconductor, is superconducting at Tc=18.5 K. This relatively high Tc is unprecedented in any other actinide system but is typical of itinerant electron compounds in which superconductivity is mediated by phonons. Recent studies of PuCoGa5 show that its superconductivity is not phonon-mediated; rather, these experiments are consistent with superconductivity produced by antiferromagnetic fluctuations of nearly localized 5f electrons. Similarities of PuCoGa5 with the superconducting and normal states of isostructural 4f analogues CeMIn5 (M=Co, Rh, Ir) and high-Tc cuprates enable new perspectives on the 5f electrons of Pu.