Interlayer coupling in ferromagnetic semiconductor superlattices

T. Jungwirth, W. A. Atkinson, B. H. Lee, and A. H. MacDonald

We developed 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, free-carrier spin polarization, finite temperature, and free-carrier exchange and correlation to be accounted for self-consistently.

As an example, we calculated the electronic structure of a Mn_xGa_1-xAs/GaAs superlattice with alternating ferromagnetic and paramagnetic layers and demonstrated the possibility of semiconductor magnetoresistance systems with designed properties [1].

Self-consistent results plotted within the unit cell of the Mn_xGa_1-xAs/GaAs superlattice. From top to bottom: (i) effective spin-dependent potentials from Eq. 6 for up (solid lines) and down (dashed lines) spin free carriers (the dotted line here indicates the chemical poten- tial); (ii) mean-field localized spin moment; (iii) free-carrier relative spin polarization.

[1] T. Jungwirth, W. A. Atkinson, B. H. Lee, and A. H. MacDonald: Phys. Rev. B 59, 9818 (1999), doi:10.1103/PhysRevB.59.9818