Common Anomalies of Transport Properties in PrTr2Zn20 (Tr=Ir, Rh) with Non-Kramers Doublet Ground State

We study the transport coefficients of PrIr2Zn20 and PrRh2Zn20 with non-Kramers doublet ground state. From the resistivity measurement, we commonly found a convex temperature dependence at high temperatures. At low temperatures, an anomaly at T* is discovered near the boundary of the antiferro-quadrupole (AFQ) ordering phase in both systems. The Fermi liquid behavior with a large electron mass is observed below T* Thus a non-trivial heavy Fermion state would be formed there. In contrast, from the quantum oscillation of the Seebeck coefficient of PrRh2Zn20, the electron mass is found to be small below the critical field for B || [110], which is consistent with negligibly mass Seebeck coefficient of PrIr2Zn20. Since these features are detected in both compounds, they are expected to be universal properties of non-Kramers systems.