title: Evolution of quantum criticality in CeNi(9-x)Cu(x)Ge(4).
abstract: Crystal structure, specific heat, thermal expansion, magnetic susceptibility and electrical resistivity studies of the heavy fermion system CeNi(9-x)Cu(x)Ge(4) (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 CeNi(9)Ge(4) (with pronounced non-Fermi-liquid features) towards a magnetically ordered, effectively twofold-degenerate ground state in CeNi(8)CuGe(4) with T(N) = 175 ± 5 mK. Quantum critical behavior, [Formula: see text], is observed for [Formula: see text]. Hitherto, CeNi(9-x)Cu(x)Ge(4) 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.
authors.affiliation: CPM, Institut für Physik, Universität Augsburg, D-86135 Augsburg, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Peyker
authors.forename: C
authors.initials: C
authors.lastname: Gold
authors.forename: E-W
authors.initials: EW
authors.lastname: Scheidt
authors.forename: W
authors.initials: W
authors.lastname: Scherer
authors.forename: J G
authors.initials: JG
authors.lastname: Donath
authors.forename: P
authors.initials: P
authors.lastname: Gegenwart
authors.forename: F
authors.initials: F
authors.lastname: Mayr
authors.forename: T
authors.initials: T
authors.lastname: Unruh
authors.forename: V
authors.initials: V
authors.lastname: Eyert
authors.forename: E
authors.initials: E
authors.lastname: Bauer
authors.forename: H
authors.initials: H
authors.lastname: Michor