Low Temperature Magnetic Properties of UAl_2 : The Kondo Effect

概要

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We have measured the specific heat in the temperature range between 1.5 and 50 K on UAl_2, classified as a paramagnetic 5f heavy fermion compound. A pronounced Schottky-like peak is observed at about 40 K with the peak height of 6 J/K mol in the electronic specific heat. Moreover, T^3 ln T temperature dependence in the specific heat is strongly suppressed below about 9 K in the case of U(Al_<1-y>Si_y)_2(0<y≤0.10), whereas no apparent change is observed for (U_<1-x>Pr_x)Al_2 (0<x≤0.15). The electronic specific heat coefficient, γ, is considerably enhanced with increasing Pr concentration. The γ-value and the inverse of the absolute value of the paramagnetic Curie temperature both for (U_<1-x>Pr_x)Al_2 and U(Al_<1-y>Si_y)_2 are varied with the lattice parameter. These behaviors are understood within the framework of the Kondo effect.
1994-10-15