Rare-earth and actinide compounds

Rare-earth and actinide compounds host electrons that move through a crystal lattice so sluggishly—due to strong interactions with localized magnetic moments—that they behave as if their mass is hundreds of times larger than a free electron, a phenomenon called heavy-fermion behavior. These materials sit at the intersection of magnetism and superconductivity, and by tuning pressure, magnetic field, or chemical composition, researchers can drive them through quantum critical points where magnetic order collapses at absolute zero, generating exotic normal-state properties like non-Fermi-liquid behavior that standard theory cannot explain. The superconductivity that often emerges near these quantum critical points is itself unconventional, likely mediated by magnetic fluctuations rather than the phonon mechanism of conventional superconductors, and in some actinide compounds may involve spin-triplet pairing with nontrivial topological character. Central open questions include precisely how quantum criticality drives Cooper pairing, how the Fermi surface reconstructs across magnetic phase transitions, and whether certain heavy-fermion superconductors can host topologically protected edge states.

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Keywords

Heavy FermionSuperconductivityQuantum CriticalityNon-Fermi-Liquid BehaviorFermi SurfaceUnconventional Superconductivity