Physical and magnetic properties of (Ce1-xNdx)3Al (x=0.3): Coexisting ferromagnetism and Kondo effect

By means of detailed electrical, magnetic and thermal studies, we illustrate the unusual coexistence of ferromagnetism and Kondo effect for the critical Nd concentration of x = 0.3 in (Ce1-xNdx)(3)Al. Magnetic susceptibility chi(T) confirms the ferromagnetic character with T-C similar to K along with Kondo effect which appears below 35 K. Non-saturating nature of magnetization (M (H)) and Hall resistivity (rho(xy) (H)) isotherms indicates the Kondo screening. Resistivity rho (T) curves exhibit nonlinear temperature dependence; similar to T-n (0.48 < n < 1) below 40 K. Higher values of Sommerfeld coefficient gamma (=321 mJ/Ln - mol-K-2) and Seebeck coefficient S (T) as compared to the parent compound Ce3Al and other Nd doped compounds in the series (Ce1-xNdx)(3)Al (x = 0-1) indicate the role of critical Nd concentration namely, 0.3 in the anomalous behavior. The high value of gamma observed in this critical concentration is unusual for a ferromagnetic compound and appears to be partially contributed by the exchange interaction due to Nd doping along with the Kondo hybridization. Suppression of gamma value with field corroborates with the resistivity data i.e., weakening of Kondo screening. Like in the case of Ce3Al, Nd doped compound also shows structural transition attributed to the valence fluctuation of Ce. chi (T), rho (T), S (T) and 4f part of specific heat, C-4f (T) data show peculiar temperature dependence and confirm the non-Fermi liquid behavior due to Ce (4f) - Nd (4f) interaction. Change in the relative strengths of Coulomb repulsion (U) and Kondo hybridization (V-fd) is found to determine the temperature dependence of thermal and thermoelectric behavior in this compound.