Effect of Si substitution on the antiferromagnetic ordering in the kondo semiconductor CeRu₂Al₁₀

We have studied the effect of 3p electron doping on the unusual antiferromagnetic (AFM) order in the Kondo semiconductor CeRu₂Al₁₀ with T_N = 27K by measuring the magnetic susceptibility χ, specific heat C, and electrical resistivity ρ for polycrystalline samples of CeRu₂Al_10-ySi_y. The large decrease in the absolute value of paramagnetic Curie temperature |θP| with increasing y indicates the suppression of c-f hybridization. The thermal activation behavior in ρ(T) above T_N disappears for y ≥ 0.3 and T_N decreases to 12K for y = 0.38. These systematic changes in |θ_P|, _ρ(T), and T_N coincide with those reported in the 4d-electron doped system Ce(Ru_1-xRh_x)₂Al₁₀ with respect to the number of doped electrons per formula unit. This coincidence indicates that the Al 3p-And Ru 4d-electrons in CeRu2Al10 play the equivalent role in both the formation of hybridization gap and the unusual AFM ordering.