Heavy fermion state and quantum criticality

• Published in: Physica. B, Condensed matter Condensed matter, 2010-05, Vol.405 (9), p.2194-2199
• Main Authors: Ōnuki, Y., Settai, R., Honda, F., Dung, N.D., Ishikura, T., Takeuchi, T., Matsuda, T.D., Tateiwa, N., Nakamura, A., Yamamoto, E., Haga, Y., Aoki, D., Homma, Y., Harima, H., Yamagami, H.
• Format: Article
• Language: English
• Subjects: Actinide compounds; Condensed matter; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Critical pressure; Cyclotrons; de Haas-van Alphen effect; Electron states; Exact sciences and technology; Fermi surface; Fermi surface: calculations and measurements; effective mass, g factor; Fermions; Mathematical analysis; Physics; Strongly correlated systems; heavy fermions; Superconductivity; Superconductors
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2010.02.006

The heavy fermion state in the f-electron systems is due to competition between the RKKY interaction and the Kondo effect. The typical compound is CeCu 6. To understand the electronic state, we studied the Fermi surface properties via the de Haas-van Alphen (dHvA) experiments and energy band calculations for CeSn 3, CeRu 2Si 2, UPt 3, and nowadays, transuranium compounds of NpGe 3 and PuIn 3, together with YbCu 2Si 2. Pressure is also an important technique to control the electronic state. For example, the Néel temperature T N decreases with increasing pressure P and becomes zero at the critical pressure P c : T N → 0 for P → P c . The typical compound is an antiferromagnet CeRhIn 5, which we studied from the dHvA experiment under pressure. A change of the 4 f-electronic state from localized to itinerant is realized at P c ≃ 2.4 GPa , revealing the first-order phase transition, together with a divergent tendency of the cyclotron mass at P c. It is stressed that appearance of superconductivity in CeRhIn 5 is closely related to the heavy-fermion state. It is also noted that the parity-mixed novel superconducting state might be realized in a pressure-induced superconductor CeIrSi 3 without inversion symmetry in the crystal structure.