Evolution of quantum criticality in CeNi9−xCuxGe4

• Published in: Journal of physics. Condensed matter 2009-06, Vol.21 (23), p.235604-235604 (9)
• Main Authors: Peyker, L, Gold, C, Scheidt, E-W, Scherer, W, Donath, J G, Gegenwart, P, Mayr, F, Unruh, T, Eyert, V, Bauer, E, Michor, H
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electronic conduction in metals and alloys; Electronic transport in condensed matter; Exact sciences and technology; Magnetic properties and materials; Magnetically ordered materials: other intrinsic properties; Physics; Scattering mechanisms and kondo effect; Valence fluctuation, kondo lattice, and heavy-fermion phenomena
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/21/23/235604

Crystal structure, specific heat, thermal expansion, magnetic susceptibility and electrical resistivity studies of the heavy fermion system CeNi9-xCuxGe4 (0 < =x < =1) reveal a continuous tuning of the ground state by Ni/Cu substitution from an effectively fourfold-degenerate non-magnetic Kondo ground state of CeNi9Ge4 (with pronounced non-Fermi-liquid features) towards a magnetically ordered, effectively twofold-degenerate ground state in CeNi8CuGe4 with TN = 175 +/- 5 mK. Quantum critical behavior,, is observed for. Hitherto, CeNi9-xCuxGe4 represents the first system where a substitution-driven quantum phase transition is connected not only with changes of the relative strength of the Kondo effect and RKKY interaction, but also with a reduction of the effective crystal field ground state degeneracy.