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

TL;DR

This study investigates how silicon substitution suppresses ferromagnetism and introduces disorder in CeRh6Ge4, revealing the effects on quantum criticality and non-Fermi liquid behavior.

Contribution

It demonstrates the impact of silicon doping on ferromagnetic order and quantum fluctuations, highlighting the role of disorder in CeRh6Ge4's quantum critical behavior.

Findings

Ferromagnetic transition suppressed at x_c≈0.125

Non-Fermi liquid behavior near x_c

Disorder affects resistivity and quantum criticality

Abstract

We report a study of isoelectronic chemical substitution in the recently discovered quantum critical ferromagnet CeRh$_6$Ge$_4$. Upon silicon-doping, the ferromagnetic ordering temperature of CeRh$_6$(Ge$_{1-x}$Si$_x$)$_4$ is continuously suppressed, and no transition is observed beyond $x_c$$\approx$0.125. Non-Fermi liquid behavior with $C/T \propto$log($T^*/T$) is observed close to $x_c$, 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 CeRh$_6$Ge$_4$, and provides further evidence for understanding the origin of this behavior.