Plutonium-Based Heavy-Fermion Systems

TL;DR

This paper reviews plutonium-based heavy-fermion systems, highlighting their complex electronic properties, large effective masses, and potential for unconventional superconductivity, emphasizing recent discoveries and ongoing challenges in understanding their behavior.

Contribution

It provides a comprehensive overview of the properties and complexities of Pu-based heavy-fermion compounds, including recent discoveries and the challenges posed by their electronic configurations.

Findings

Twelve Pu-based heavy-fermion compounds identified.

Large effective electron masses observed in these systems.

Potential for unconventional superconductivity discussed.

Abstract

An effective mass of charge carriers that is significantly larger that the mass of a free electron develops at low temperatures in certain lanthanide- and actinide-based metals, including those formed with plutonium, due to strong electron-electron interactions. This heavy-fermion mass is reflected in a substantially enhanced electronic coefficient of specific heat $\gamma$, which for elemental Pu itself is much larger than that of normal metals. By our definition, there are twelve Pu-based heavy-fermion compounds, most discovered recently, whose basic properties are known and discussed. Relative to other examples, these Pu-based heavy-fermion systems are particularly complex due in part to the possible simultaneous presence of multiple, nearly degenerate 5f$^n$ configurations. This complexity poses significant opportunities as well as challenges, including understanding the origin of unconventional superconductivity in some of these materials.