Spin-dependent masses and field-induced quantum critical points

✍ Scribed by A. McCollam; R. Daou; S.R. Julian; C. Bergemann; J. Flouquet; D. Aoki

• Publisher: Elsevier Science
• Year: 2005
• Tongue: English
• Weight: 281 KB
• Volume: 359-361
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/j.physb.2004.12.039

✦ Synopsis

We discuss spin-dependent mass enhancements associated with field-induced quantum critical points in heavyfermion systems. We have recently observed this phenomenon on a branch of the Fermi surface of CeRu 2 Si 2 above its metamagnetic transition, complementing earlier work. In CeCoIn 5 ; at high fields above a field-induced quantum critical point, we see a strong spin-dependence of the effective mass on the thermodynamically dominant sheets of the Fermi surface. These observations reinforce the suggestion that 'missing mass' in some cerium-based heavy-fermion systems will be found on heavy spin-polarised branches of the Fermi surface. In all cases where this phenomenon is observed the linear coefficient of specific heat is field dependent; however, CeCoIn 5 seems to be the first such heavy-fermion system in which the f-electrons are definitely contributing to the Fermi volume, which puts it beyond the existing theory intended for metamagnetic systems.