A Study of Ni-Substitution Effects on Heavy-Fermion CeCu2Si2 - Similarities between Ni Substitution and High-Pressure Effects -

TL;DR

This study investigates how Ni substitution influences the quantum critical behavior and superconductivity in CeCu2Si2, revealing similarities to high-pressure effects and highlighting a crossover from Kondo to valence fluctuation regimes.

Contribution

It demonstrates that Ni substitution suppresses quantum fluctuations and induces a Fermi liquid state, with behaviors analogous to high-pressure effects, providing new insights into tuning heavy-fermion properties.

Findings

Quantum fluctuations are suppressed by Ni substitution.

Fermi liquid state recovers in Ni-rich regions (x > 0.12).

T-linear resistivity appears near x ~ 0.10, indicating crossover behavior.

Abstract

The effects of Ni substitution on Ce(Cu1-xNix)2Si2 have been studied by specific heat and electrical resistivity measurements. The specific heat measurement has revealed that the enhanced quantum fluctuations around an antiferromagnetic quantum critical point are markedly suppressed by Ni substitution, and that the Fermi liquid state recovers in the Nirich region (x > 0.12). The characteristic T-linear dependence of the resistivity has been observed at approximately x ~ 0.10 together with a sign of superconductivity. The variation of n in the form of rho - rho0 = aT^n against Tmax^1, at which the resistivity peaks, coincides with the case of high-pressure experiments on pure CeCu2Si2. The anomalous T-linear behavior appears to occur in the crossover region from the Kondo regime to the valence fluctuation regime rather than in the conventional antiferromagnetic quantum critical region.