The ternary gallium-rich ${\mathrm{Y}}_2{\mathrm{Co}}_3{\mathrm{Ga}}_9$-type compound, ${\mathrm{Ce}}_2{\mathrm{Rh}}_3{\mathrm{Ga}}_9$ and its non-$4f$-electron isostructural counterpart ${\mathrm{La}}_2{\mathrm{Rh}}_3{\mathrm{Ga}}_9$ have been successfully synthesized using the conventional arc-melting method. The physical properties were determined by means of x-ray powder diffraction (XRD), magnetic susceptibility $\chi \left(T\right)$, isothermal magnetization $M$($B$), specific heat $C_p\left(T\right)$, electrical resistivity $\rho \left(T\right)$, and thermopower $S$ ($T$) measurements. In addition, a first-principles density functional theory (DFT) investigations have been used to further explore the thermophysical and electron structure properties. The XRD crystal structure determination at room temperature has revealed that both compounds have the orthorhombic ${\mathrm{Y}}_2{\mathrm{Co}}_3{\mathrm{Ga}}_9$-type crystal structure, with the space group Cmcm. $\chi \left(T\right), C_p\left(T\right)$, and $\rho \left(T\right)$ measurements performed in a wide temperature range reveal that ${\mathrm{La}}_2{\mathrm{Rh}}_3{\mathrm{Ga}}_9$ is a weakly interacting, nonmagnetic metal with $\gamma =7.5\mathrm{mJ}/\mathrm{La}\text{−}\mathrm{mol}{\mathrm{K}}^2$. On the other hand, for ${\mathrm{Ce}}_2{\mathrm{Rh}}_3{\mathrm{Ga}}_9$ the same measurements, plus $S$ ($T$) uncover the features usually found in the heavy-fermion Kondo lattice class of materials with a strong impact of the crystal field effect (CEF). The characteristic parameters estimated for this material, such as Kondo temperature and the Sommerfeld coefficient, are respectively $T_K=14.7\mathrm{K}$ and $\gamma =100\mathrm{mJ}/\mathrm{Ce}\text{−}\mathrm{mol}{\mathrm{K}}^2$. Additionally, at low temperatures, the Ce-based compound is found to exhibit the $-\ln T$ behavior of the ratio $C_p\left(T\right)/T$, without exhibiting any phase transition down to 1.9 K. Also, the measurements of $\rho \left(T\right)$ performed down to 0.4 K showed no anomaly that might evidence the presence of a phase transition. Such a low-$T$ logarithmic upturn in specific heat, together with the observed enhancement in the thermodynamic effective mass of the fermionic quasiparticles, as well as an anomalous power law temperature dependence of the $\rho \left(T\right) \sim {\rho }_{\text{el-el}}{T}^{1.5}$ signals Fermi liquid breakdown, likely connected to the presence of a quantum critical point at $T \to 0\mathrm{K}$. The remarkably large values of the slope $S\left(T\right)/T$ have also been noted for the low-$T$ regime.

Close

PrevNext

View figure in article

• Electrical properties
• Electronic structure
• First-principles calculations
• Kondo effect
• Specific heat
• Structural properties
• Thermoelectric effects
• Heavy-fermion systems
• Strongly correlated systems
• Approximation methods for many-body systems
• Boltzmann theory
• Density functional theory
• Fermi liquid theory
• Resistivity measurements
• Specific heat measurements
• X-ray diffraction