LATTICE COHERENCE VERSUS INCOHERENT METAL IN THE LATTICE N-CHANNEL KONDO MODEL

We consider the lattice extension of the SU(N) x SU(M) generalization of the multichannel Kondo problem. Within the noncrossing approximatio n, the effect of the lattice is of order 1/N and, therefore, the behav ior of the system is qualitatively the same as for the single-impurity case. The density of states at the Fermi energy is finite, leading to an incoherent metal. At sufficiently low temperatures lattice coheren ce should prevail. We estimate the temperature at which the spin and c hannel susceptibilities have an instability, summing analytically the ladder series for the spin and channel vertices. We find an antiferrom agnetic instability and no ferromagnetic instability in the spin susce ptibility and a zero-momentum instability in the channel susceptibilit y. [S0163-1829(98)08641-X].