Suppression of ferromagnetism and influence of disorder in silicon-substituted CeRh6Ge4

Abstract

We report a study of isoelectronic chemical substitution in the recently discovered quantum critical ferromagnet CeRh6Ge4. Upon silicon-doping, the ferromagnetic ordering temperature of CeRh6(Ge1−xSix)4 is continuously suppressed, and no transition is observed beyond xc≈0.125. Non-Fermi liquid behavior with C/T ∝log(T * /T ) is observed close to xc, indicating the existence of strong quantum fluctuations, while the T -linear behavior observed upon pressurizing the parent compound is absent in the resistivity, which appears to be a consequence of the disorder induced by silicon doping. Our findings provide evidence for the role played by disorder on the unusual ferromagnetic quantum criticality in CeRh6Ge4, and provides further evidence for understanding the origin of this behavior.