We show that the low-temperature fixed-point behavior of the negative-U Anderson model involves a ‘‘charge Kondo effect,’’ where the local pair behaves as a Heisenberg rather than an xy degree of freedom. Interactions of the local pair with the conduction sea generate a highly polarizable Fermi liquid with enhanced linear specific heat and charge and pair susceptibilities.

• Received 18 October 1990

DOI:https://doi.org/10.1103/PhysRevLett.66.2814