Effect of Ga Substitution on the Γ3 Doublet Ground State in PrIr2Zn20

Abstract

Electrical resistivity ρ, specific heat C, and magnetic susceptibility χ measurements are reported on PrIr2Zn20-xGax for x=0.5 and 1.0. On cooling, ρ(T)'s monotonically decrease to the residual values which are two orders of magnitudes larger than that of PrIr2Zn20. A broad hump in Cm(T)'s at around 10 K can be reproduced by the two-level model with the Γ3 doublet ground state and the Γ4 triplet excited state. The magnetic entropy release shifts to higher temperatures with increasing x. The increase in χ(T) at T < 5 K contrasts with the saturation of χ(T) for x=0. These observations indicate the splitting of the ground state doublet due to the lowering of the local symmetry at the Pr site by the Ga substitution.