PHOTOELECTRON SPECTROSCOPY IN STUDIES OF THE BAND STRUCTURE OF IV-VI SPINTRONIC MATERIALS

Among several groups of chemical compounds exploited in the quest for materials suitable for spintronic application diluted magnetic semiconductors have particular set of properties. Although the ferromagnetic transition temperatures observed in such systems are still markedly below the room temperature, their electronic characteristics, similar to those of the host semiconducting system, and the compatibility with electronic device technology are obvious advantages. Ge1-xMnxTe, a member of the IV-VI semiconductor family, attracts considerable interest due to the relatively high Curie temperature-it can be as high as 190 K [1]. This inspired extensive investigations of this solid solution and development of technological methods in view of increase of the ferromagnetic transition temperature. The magnetic properties of systems based on IV-VI semiconductors depend on the interaction between the magnetic ions mediated by charge carriers of the host semiconductor. The interaction is successfully described by the RKKY model. As a consequence, knowledge of electronic band structure of such materials is important for understanding their transport, optical, and also magnetic properties. We present a set of experimental results, acquired by photoelectron spectroscopy, showing the electronic structure of Ge1-xMnxTe in comparison with GeTe and results of ab initio pseudopotential calculations.