Magneto-optical properties of PbTe and PbSe alloyed with paramagnetic ions Mn and Eu are reviewed. The k . p theory of the band structure of IV-VI compounds is presented, taking into account the narrow energy gaps and strong spin-orbit interactions in the materials. The exchange interaction between the paramagnetic ions and mobile carriers is included in the framework of the meanfield approximation. The experimental data of various authors on magnetization, interband magneto-optics. intraband magneto-optics and four-wave mixing are presented. All results are successfully described by the theory, treating the exchange integrals as adjustable parameters. It is shown that the exchange interaction is of particular importance for the valence bands. Differences between semimagnetic behaviours of Mn-based and Eu-based systems are emphasized as well as those between the IV-VI and Il-VI semimagnetic compounds.

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Multilayers of strained metamagnetic EuSe intercalated with nonmagnetic PbSe1-xTex were grown by molecular beam epitaxy under conditions optimized by electron diffraction. From detailed structural and magnetic characterization using anomalous synchrotron x-ray diffraction and magnetization measurements, the phase transition temperatures and the magnetic phase diagrams of strained EuSe as a function of the in-plane lattice constant are determined. In this way, it is demonstrated that the magnetic properties of the samples can be significantly changed by applying biaxial strain on EuSe in superlattice structures.

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