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arXiv · 1110.6090

Evolution of quantum criticality in the system CeNi9Ge4

H. Michor·D. T. Adroja·A. D. Hillier·M. M. Koza·S. Manalo·C. Gold·L. Peyker·E. -W. Scheidt
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Abstract

The heavy fermion system CeNi9Ge4 exhibits a paramagnetic ground state with remarkable features such as: a record value of the electronic specific heat coefficient in systems with a paramagnetic ground state, \gamma = C/T \simeq 5.5 J/molK^2 at 80 mK, a temperature-dependent Sommerfeld-Wilson ratio, R=\chi/\gamma, below 1 K and an approximate single ion scaling of the 4f-magnetic specific heat and susceptibility. These features are related to a rather small Kondo energy scale of a few Kelvin in combination with a quasi-quartet crystal field ground state. Tuning the system towards long range magnetic order is accomplished by replacing a few at.% of Ni by Cu or Co. Specific heat, susceptibility and resistivity studies reveal T_N \sim 0.2 K for CeNi8CuGe4 and T_N \sim 1 K for CeNi8CoGe4. To gain insight whether the transition from the paramagnetic NFL state to the magnetically ordered ground state is connected with a heavy fermion quantum critical point we performed specific heat and ac susceptibility studies and utilized the \mu SR technique and quasi-elastic neutron scattering.

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H. Michor, D. T. Adroja, A. D. Hillier, M. M. Koza, S. Manalo, C. Gold, L. Peyker, E. -W. Scheidt. 2011-10-27. Evolution of quantum criticality in the system CeNi9Ge4. https://doi.org/10.1088/1742-6596/344/1/012001

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