Abstract
Electromagnetic properties of ferrites are discussed, with special regard to the garnet
and spinel structures. In the compound yttrium iron garnet, Y 3Fe50i2, small amounts of
tetravalent dopants, like silicon, induce charge compensating Fe2+ ions. A discussion is
given of the time-dependent magneto-crystalline anisotropy caused by the presence of the
Fe2+ ions. At temperatures below about 100K, a number of physical properties of silicondoped
iron garnets can be changed by irradiation with infrared light. Examples are given
of photoinduced changes in magnetocrystalline anisotropy, magnetic susceptibility and
coercive force. Further, we discuss related photoinduced changes in the optical absorption
coefficient and in linear dichroism. The effects are divided into two different classes:
I) photoinduced effects which depend on the direction of the magnetization with respect to
the crystallographic axes and the polarization direction of the incident light, and II) photoinduced
effects that occur regardless of the prevailing magnetization distribution. In case I
the effects are due to an unequal distribution of Fe2+ ions over sites which have a different
orientation of their local symmetry axis with respect to the magnetization direction. In
case II the photoinduced effects are due to a redistribution of Fe2+ ions over sites at different
distances from the electron donating centre, e.g. the Si4+ ion. Finally magneto-optic effects
in ferrites are considered. After a discussion of the phenomenological theory, the Faraday
effect in the microwave and infrared region and the Faraday and Kerr effects at optical
frequencies are considered.
Original language | English |
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Title of host publication | Interaction of radiation with condensed matter : lectures presented at an international winter college, Trieste, 14 January - 26 March 1976, vol. 2 |
Place of Publication | Vienna |
Publisher | International Atomic Energy Agency |
Pages | 159-221 |
ISBN (Print) | 92-0-130477-3 |
Publication status | Published - 1977 |