Interlayer coupling in ferromagnetic semiconductor superlattices

We develop a mean-field theory of carrier-induced ferromagnetism in diluted magnetic semiconductors. Our approach represents an improvement over standard Ruderman-Kittel-Kesuya-Yosida model allowing spatial inhomogeneity of the system, fi ee-carrier spin polarization, finite temperature, and free-carrier exchange and correlation to be accounted for self-consistently. As an example, we calculate the electronic structure of a MnxCa1-xAs/GaAs superlattice with alternating ferromagnetic and paramagnetic layers and demonstrate the possibility of semiconductor magnetoresistance systems with designed properties. [S0163-1829(99)02816-7].