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

TL;DR

This study investigates the quantum critical point in CeCo$_{1-x}$Fe$_x$Ge$_3$ alloys, revealing non-Fermi liquid behavior and complex magnetic phases through comprehensive experimental analysis.

Contribution

It provides the first detailed phase diagram and evidence of non-Fermi liquid behavior near the quantum critical point in CeCo$_{1-x}$Fe$_x$Ge$_3$ alloys.

Findings

Quantum critical point identified at x~0.6.

Non-Fermi liquid behavior confirmed by multiple measurements.

Enhanced Seebeck coefficient near the QCP.

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.