Ubiquity of unconventional phenomena associated with critical valence fluctuations in heavy fermion metals

Abstract

Ubiquity of unconventional phenomena observed in a series of heavy fermion metals is discussed on the basis of an idea of critical valence fluctuations. After surveying experimental aspects of these unconventional behaviors in prototypical compounds, , under pressure, we propose that sharp valence crossover phenomena are realized in , , and by tuning the pressure and the magnetic field simultaneously, on the basis of previous results for an extended Anderson lattice model with the Coulomb repulsion between localized f-electron and itinerant conduction electrons.

Keywords:

• Critical valence fluctuations
• unconventional criticality
• CeCu₂(Si,Ge)₂
• CeCu₆
• CeRhIn₅
• Ce(Ir,Rh)Si₃

Acknowledgements

We acknowledge J. Flouquet, A. T. Holmes, D. Jaccard, H. Maebashi, O. Narikiyo, Y. Onishi, and A. Tsuruta for long collaborations on physics of CVF on which a considerable part of the present article is based. Discussions and conversations with K. Deguchi, K. Fujiwara, H. Kobayashi, T. C. Kobayashi, K. Kuga, Y. Matsumoto, S. Nakatsuji, and N. K. Sato on experimental data are also acknowledged.

Notes

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work is supported by the Grant-in-Aid for Scientific Research [grant number 24540378], [grant number 25400369], [grant number 15K05177], [grant number 16H01077]; from the Japan Society for the Promotion of Science. One of us (S.W.) was supported by JASRI [Proposal number 0046 in 2012B, 2013A, 2013B, 2014A, 2014B, 2015A].