Effect of 3p- and 5d-electron doping on the Kondo Semiconductor CeFe2Al10

We examined the effect of 3p- and 5d-electron doping on the Kondo semiconductor CeFe2Al10 by means of the electrical resistivity (ρ), magnetic susceptibility (χ), and specific heat (C) measurements. The results show that in the 3p-electron-doped system CeFe2Al10−y Si y , the semiconducting behavior is suppressed for y = 0.05, and the system adopts a metallic ground state with an increase in the density of states at the Fermi level. The Si substitution leads to a large decrease in the paramagnetic Weiss temperature θP indicating a reduction in c-f hybridization strength, however the Si does not induce magnetic order up to y = 0.3 down to 2K. The systematic changes in ρ(T), χ(T), and C(T) are similar to those for 5d-electron doped system CeFe2−x Ir x Al10, although, Ir substitution induces a bulk antiferromagnetic transition below 3.1 K in CeFe1.7Ir0.3Al10. These changes can be explained by the collapse of the hybridization gap due to the suppression of the c-f hybridization effect. Our results further confirm that the collapse of the spin/charge gap by an excess electron doping is one of the universal features of the Kondo semiconductors CeT 2Al10 (T = Fe, Ru, and Os).