Tailoring spin ordering in magnetic semiconductors

This paper reviews the current status and prospects of research on ferromagnetism in tetrahedrally coordinated magnetic semiconductors and their nanostructures. Results of a quantitative comparison between experimental and theoretical results, notably for Mn-based III-V and II-VI thin films and heterostructures, are presented. This comparison demonstrates that the current theory of the hole-mediated exchange interactions describes correctly the values of Curie temperatures Tc, magnetic anisotropy, and magnetic circular dichroism. On this basis, chemical trends are e examined and show to lead to the prediction of semiconductor systems with Te that may exceed room temperature. Furthermore, the important issue of tailoring magnetic properties by electrostatic or ferromagnetic gates, by confinement or illumination, by exchange bias or strain are discussed. The interesting question of designing spatially modulated magnetic structures in quantum structures is addressed, too. Finally, hopes associated with materials containing magnetic ions other than Mn are mentioned. (C) 2001 Elsevier Science B.V. All rights reserved.