Complex magnetism and non-Fermi liquid state in the vicinity of the quantum critical point in the CeCo${}_{1-x}$Fe${}_x$Ge${}_3$ series

Abstract

We report extensive studies on the CeCo${}_{1-x}$Fe${}_x$Ge${}_3$ alloys, which show quantum critical point (QCP) due to damping the antiferromagnetic order in CeCoGe${}_3$ down to 0 K by doping with the paramagnetic CeFeGe${}_3$ compound. The presence of QCP is confirmed by detecting the non-Fermi liquid behavior (NFL) using a wide range of the experimental methods: magnetic susceptibility, specific heat, electrical resistivity, magnetoresistance, and thermoelectric power. In the case of the thermoelectric power we find a clear enhancement of the Seebeck coefficient for $x$ around 0.6, i.e. in the neighborhood of QCP. Finally, the different complementary studies enabled construction of the complex magnetic phase diagram for the CeCo${}_{1-x}$Fe${}_x$Ge${}_3$ system, including the energy scale imposed by the crystal electric field splitting of the Ce ground state.