Synthesis and physical properties of Ce2Rh3+δSb4 single crystals

Millimeter-sized ${\mathrm{Ce}}_{2}{\mathrm{Rh}}_{3+\ensuremath{\delta}}{\mathrm{Sb}}_{4}$ ($\ensuremath{\delta}\ensuremath{\approx}1/8$) single crystals were synthesized by a Bi-flux method, and their physical properties were studied by a combination of electrical transport, magnetic, and thermodynamic measurements. The resistivity anisotropy ${\ensuremath{\rho}}_{a,b}/{\ensuremath{\rho}}_{c}\ensuremath{\sim}2$, manifesting a quasi-one-dimensional electronic character. Magnetic susceptibility measurements confirm $\mathbf{ab}$ as the magnetic easy plane. A long-range antiferromagnetic transition occurs at ${T}_{N}=1.4$ K, while clear short-range ordering can be detected well above ${T}_{N}$. The low ordering temperature is ascribed to the large Ce-Ce distance as well as the geometric frustration. Kondo scale is estimated to be about 2.4 K, comparable to the strength of magnetic exchange. ${\mathrm{Ce}}_{2}{\mathrm{Rh}}_{3+\ensuremath{\delta}}{\mathrm{Sb}}_{4}$, therefore, represents a rare example of a dense Kondo lattice whose Ruderman-Kittel-Kasuya-Yosida exchange and Kondo coupling are both weak but competing.