Peyker L, Gold C, Scheidt E-W, Scherer W, Donath J G, Gegenwart P, Mayr F, Unruh T, Eyert V, Bauer E, Michor H
CPM, Institut für Physik, Universität Augsburg, D-86135 Augsburg, Germany.
J Phys Condens Matter. 2009 Jun 10;21(23):235604. doi: 10.1088/0953-8984/21/23/235604. Epub 2009 May 15.
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.
对重费米子体系CeNi(9 - x)Cu(x)Ge(4)（0≤x≤1）的晶体结构、比热、热膨胀、磁化率和电阻率研究表明，通过Ni/Cu替代可对基态进行连续调节，从CeNi(9)Ge(4)的有效四重简并非磁性近藤基态（具有明显的非费米液体特征）转变为CeNi(8)CuGe(4)中具有T(N) = 175 ± 5 mK的磁有序、有效二重简并基态。对于[公式：见文本]，观察到量子临界行为[公式：见文本]。迄今为止，CeNi(9 - x)Cu(x)Ge(4)代表了第一个体系，其中替代驱动的量子相变不仅与近藤效应和RKKY相互作用的相对强度变化有关，还与有效晶体场基态简并度的降低有关。
