HEAVY-FERMION-LIKE EXCITATIONS IN METALLIC ND2-YCEYCUO4

The specific heat of Nd2-yCeyCuO4, 0 less-than-or-equal-to y less-than-or-equal-to 0.2, was measured between 35 mK and 10 K. A Schottky anomaly in Nd2CuO4, due to exchange interactions between Nd and Cu moments, shifts upon Ce doping to lower temperatures. In the metallic state (y greater-than-or-equal-to 0.15), a linear term with coefficient gamma congruent-to 4J/K2 per mole Nd is found below 300 mK. For y = 0.2, a constant value of the magnetic susceptibility in the same temperature range and changes of C(p) in applied magnetic fields suggest an interpretation in analogy to a heavy-fermion system resulting from the coupling between Nd moments and conduction electrons.