Strong coupling in the Kondo problem in the low-temperature region

The magnetic field dependence of the average spin of a localized electron c oupled to conduction electrons with an antiferromangetic exchange interacti on is found for the ground state. In the magnetic field range mu H similar to 0.5T(c) (T-c is the Kondo temperature) there is an inflection point, and in the strong magnetic field range mu H much greater than T-c, the correct ion to the average spin is proportional to (T-c/mu H)(2). In zero magnetic field, the interaction with conduction electrons also leads to the splittin g of doubly degenerate spin impurity states. (C) 1999 American Institute of Physics. [S1063-7761(99)00804-5].