KONDO CROSSOVER IN THE SELF-CONSISTENT ONE-LOOP APPROXIMATION

The free energy and magnetization for the general SU(N) one-impurity K ondo model in the magnetic field h are calculated by extending the pre vious 1/N expansion technique: the saddle point is determined self-con sistently to the 1/N order. The obtained universal field-dependent mag netization M(h/T(K)) by this simple method is shown analytically to be asymptotically exact at both h much less than T(K) and h much greater than T(K) limits. For general ''f-electron'' fillings, except half fi lling, the M(h/T(K)) curves cross continuously from the weak to strong coupling limit, but overestimate the curvature in the crossover regio n for moderate N. The magnetic Wilson crossover numbers are calculated approximately. Our results explicitly verify that the 1/N parameter i s nonsingular under the adiabatic continuation.