The Nature and Validity of the RKKY limit of exchange coupling in   magnetic trilayers
  The effects on the exchange coupling in magnetic trilayers due to the presence of a spin-independent potential well are investigated. It is shown that within the RKKY theory no bias nor extra periods of oscillation associated with the depth of the well are found, contrary to what has been claimed in recent works. The range of validity of the RKKY theory is also discussed. 
M. S. Ferreira, R. B. Muniz, J. d'Albuquerque e Castro and D. M.   Edwards