Valence instability and superconductivity in heavy fermion systems

A.T. Holmes, D. Jaccard, K. Miyake

Research output: Contribution to journalArticlepeer-review

87 Citations (Scopus)
228 Downloads (Pure)


Many cerium-based heavy fermion (HF) compounds have pressure-temperature phase diagrams in which a superconducting region extends far from a magnetic quantum critical point. In at least two compounds, CeCu Si and CeCu Ge , an enhancement of the superconducting transition temperature was found to coincide with an abrupt valence change, with strong circumstantial evidence for pairing mediated by critical valence, or charge transfer, fluctuations. This pairing mechanism, and the valence instability, is a consequence of a f-c Coulomb repulsion term U in the Hamiltonian. While some non-superconducting Ce compounds show a clear first order valence instability, analogous to the Ce α-γ transition, we argue that a weakly first order valence transition may be a general feature of Ce-based HF systems, and both magnetic and critical valence fluctuations may be responsible for the superconductivity in these systems.
Original languageEnglish
Article number051002
JournalJournal of the Physical Society of Japan
Issue number5
Publication statusPublished - 1 May 2007


Dive into the research topics of 'Valence instability and superconductivity in heavy fermion systems'. Together they form a unique fingerprint.

Cite this