Evolution of Quantum Criticality in CeNi_{9-x}Cu_xGe_4

Abstract

Crystal structure, specific heat, thermal expansion, magnetic susceptibility and electrical resistivity studies of the heavy fermion system CeNi_{9-x}Cu_xGe_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_9Ge_4 (with pronounced non-Fermi-liquid features) towards a magnetically ordered, effectively twofold degenerate ground state in CeNi_8CuGe_4 with T_N = 175 +- 5 mK. Quantum critical behavior, C/T ~ χ~ -ln(T), is observed for x about 0.4. Hitherto, CeNi_{9-x}Cu_xGe_4 represents the first system where a substitution-driven quantum phase transition is connected not only with changes of the relative strength of Kondo effect and RKKY interaction, but also with a reduction of the effective crystal field ground state degeneracy.

15 pages, 9 figures

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Cited by in corpus (8)

• Crystal fields and Kondo effect: specific heat for Cerium compounds
• Competing magnetic interactions in CeNi9-xCoxGe4
• Antiferromagnetic behavior in CeCo${}_9$Ge${}_4$
• Evolution of quantum criticality in the system CeNi9Ge4
• Learning crystal field parameters using convolutional neural networks
• Crystal field studies on the heavy fermion compound CeNi${}_8$CuGe${}_4$
• Evolution of single-ion crystal field and Kondo features in Ce${}_{0.5}$La${}_{0.5}$Ni${}_{9-x}$Cu${}_x$Ge${}_4$
• Low temperature thermomagnetic properties of very heavy fermions suitable for adiabatic demagnetization refrigeration