Doniach Phase Diagram, Revisited: From Ferromagnet to Fermi Liquid in PressurizedCeRu2Ge2

Abstract

We present the resistivity and ac susceptibility of $\mathrm{CeRu}{}_{2}\mathrm{Ge}{}_{2}$ at pressures $p$ up to 130 kbar. Pressure transforms the system from a ferromagnet into a nonordering Fermi liquid (FL). The suppression of magnetic order at ${p}_{c}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}67\mathrm{kbar}$ is accompanied by non-Fermi liquid (NFL) behavior. By comparing our results to isoelectronic $\mathrm{CeRu}{}_{2}(\mathrm{Ge}{}_{1\ensuremath{-}x}\mathrm{Si}{}_{x}{)}_{2}$ we derive a unified hybridization $J$ phase diagram for the entire material class. The phase diagram is characterized by the FL and Kondo energy scales ${T}_{\mathrm{FL}}$ and ${T}_{K}$, with the NFL behavior appearing at ${T}_{\mathrm{FL}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0\mathrm{K}$, while ${T}_{K}$ remains finite and a smoothly increasing function of $J$.