Evolution of single-ion crystal field and Kondo features in Ce${}_{0.5}$La${}_{0.5}$Ni${}_{9-x}$Cu${}_x$Ge${}_4$

Abstract

Starting with the heavy fermion compound CeNi${}_9$Ge${}_4$, the substitution of nickel by copper leads to a dominance of the RKKY interaction in competition with the Kondo and crystal field interaction. Consequently, this results in an antiferromagnetic phase transition in CeNi${}_{9-x}$Cu${}_x$Ge${}_4$ for $x>0.4$, which is, however, not fully completed up to a Cu-concentration of $x=1$. To study the influence of single-ion effects on the AFM ordering by shielding the $4f$-moments, we analyzed the spin diluted substitution series La${}_{0.5}$Ce${}_{0.5}$Ni${}_{9-x}$Cu${}_x$Ge${}_4$ by magnetic susceptibility $\chi$ and specific heat $C$ measurements. For small Cu-amounts $x\le 0.4$ the data reveal single-ion scaling with regard to the Ce-concentration, while for larger Cu-concentrations the AFM transition (encountered in the CeNi${}_{9-x}$Cu${}_x$Ge${}_4$ series) is found to be completely depressed. Calculation of the entropy reveal that the Kondo-effect still shields the 4$f$-moments of the Ce${}^{3+}$-ions in CeNi${}_8$CuGe${}_4$.

4 pages, 3 figures, conference SCES09

References in corpus (1)

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