Intermediate valence to heavy fermion through a quantum phase transition in Yb3(Rh1-xTx)4Ge13 (T = Co, Ir) single crystals.

Single crystals of Yb3(Rh1-xTx )4Ge13 (T = Co, Ir) have been grown using the self-flux method. Powder x-ray diffraction data on these compounds are consistent with the cubic structure with space group Pm3n. Intermediate-valence behavior is observed in Yb3(Rh1-xTx )4Ge13 upon T = Co doping, while T = Ir doping drives the system into a heavy-fermion state. Antiferromagnetic order is observed in the Ir-doped samples Yb3(Rh1-xTx )4Ge13 for 0.5 < x ⩽ 1 with TN = 0.96 K for Yb3Ir3Ge13. With decreasing x, the magnetic order is suppressed towards a quantum critical point around Xc = 0.5, accompanied by non-Fermi-liquid behavior evidenced by logarithmic divergence of the specific heat and linear temperature dependence of the resistivity. The Fermi-liquid behavior is recovered with the application of large magnetic fields. [ABSTRACT FROM AUTHOR]