Ferromagnetic semiconductors

Abstract

The current status and prospects of research on ferromagnetism in\nsemiconductors are reviewed. The question of the origin of ferromagnetism in\neuropium chalcogenides, chromium spinels and, particularly, in diluted magnetic\nsemiconductors is addressed. The nature of electronic states derived from 3d of\nmagnetic impurities is discussed in some details. Results of a quantitative\ncomparison between experimental and theoretical results, notably for Mn-based\nIII-V and II-VI compounds, are presented. This comparison demonstrates that the\ncurrent theory of the exchange interactions mediated by holes in the valence\nband describes correctly the values of Curie temperatures T_C magnetic\nanisotropy, domain structure, and magnetic circular dichroism. On this basis,\nchemical trends are examined and show to lead to the prediction of\nsemiconductor systems with T_C that may exceed room temperature, an expectation\nthat are being confirmed by recent findings. Results for materials containing\nmagnetic ions other than Mn are also presented emphasizing that the double\nexchange involving hoping through d states may operate in those systems.\n