Resonant exchange interaction in semiconductors

We present a non-perturbative calculation of indirect exchange interaction between two paramagnetic impurities via 2D free carriers gas separated by a tunnel barrier. The new method accounts for the impurity attractive potential producing a bound state. The calculations show that for if the bound impurity state energy lies within the energy range occupied by the free 2D carriers the indirect exchange interaction is strongly enhanced due to resonant tunneling and exceeds by a few orders of magnitude what one would expect from the conventional RKKY approach.