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We have been studying magnetic properties of magnetic ion clusters in ternary, quaternary, and quinary IV-VI and II-IV-V 2 diluted magnetic semiconductors with varying concentrations of different magnetic and non-magnetic cations. We observed clusters of different types, from non-random distribution of magnetic ions in the host lattice to precipitates with the crystalline structure different from that of the host. The size of such precipitates varied from 200 nm to 20 μm. Depending on the type and size of clusters we observed different magnetic properties of the compounds, such as paramagnetic, spin-glass, spin-glass-like, or ferromagnetic states. For example, Zn 1-x Mn x GeAs 2 compounds with x ≤ 0.053 were paramagnetic with evidence of small short-range magnetic interactions, while in the same material with x ≥ 0.078 we observed room-temperature ferromagnetism. In IV-VI DMS clusters usually created a spin-glass or spinglass- like state. However, in some Ge 1-x-y Pb x Mn y Te crystals we observed a co-existence of two very different spin-glasslike states with transition temperatures T 1 ≈ 5 K and T 2 ≈ 90 K.

fraction of the magnetic centers increases with the increase of the Yb content, but is significantly lower than the total Ybconcentration in the investigated alloys. The obtained results are explained taking into account existing of magnetic Yb3and nonmagnetic Yb2 ions in the alloys and the possibility oftransition of ions from one state to the other due to shift of theYb impurity level with respect to the valence band edge as the composition ofthe alloy changes.Keywords: IV-VI semiconductors, magnetic ions, deep impurity levels

In this paper galvanomagnetic properties and photoconductivity kinetics in Pb1-xGexTe alloys doped with Yb were investigated. The existing of Yb-induced level near the valence band top was established. High photosensitivity at temperature under 30 K and the effect of persistent photoconductivity at helium temperature were found. The photoconductivity kinetics revealed two types of relaxation processes: a fast one and a long duration one, that was explained assuming that doping with Yb leads to the formation of reconstructing Jahn-Teller centers in Pb1-xGexTe alloys.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Epitaxial films Pb1-x-yGeySnxTe:In grown by 'hot wall' method on insulating substrates BaF2 are studied. Samples are made in Ukrainian Institute of Problems of the Study of Materials. Measurements of photoconductivity spectra and temperature dependence of resistance are carried out at different background fluxes. The correlation between a cutoff wavelength and thermoactivation energies of resistance of studied samples was observed. The observed phenomena are explained on the basis of a two-electron Indium impurity center model. Energies of local oscillations of impurity centers are determined.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.