Fe Substitution Effect On The High-Field Magnetization In The Kondo Semiconductor Ceru2al10

The magnetization of the Fe substitution system in the Kondo semiconductor CeRu2Al10 was measured in high magnetic fields of up to 72 T with the magnetic field (H) along the a-axis. The magnetization curve indicates that the critical field from the antiferromagnetic (AFM) phase to the paramagnetic one (H-c(p)) shows an increase from similar to 51 (x = 0) to similar to 60 T (x = 0.7) owing to the Fe substitution. The Fe concentration dependence of H-c(p) is similar to that of the magnitude of the energy of the spin gap. The degree of the concave H dependence of the magnetization curve, which is the characteristic feature for H parallel to a in CeT2Al10 (T = Ru, Os), is not strongly enhanced by the Fe substitution. This may be due to the suppression of the strong anisotropy of the hybridization between the conduction band and the localized 4f shell along the a-axis. These results reveal that the spin gap of the present system consists of at least two components, the gap due to the spin (Kondo) singlet formation and the anisotropy gap of the AF magnon.