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Magnetic and luminescent properties of ZnSe crystals doped with Fe by various methods are studied. It is established that Fe impurity is responsible for photoluminescence (PL) bands at 980, 1320, 1450 nm and quenches PL band at 630–645 nm. It is found that magnetic properties of ZnSe:Fe crystals are sensitive to the doping method. At low fields, two magnetic subsystems may be observed for the samples doped with Fe during the growth process—weak paramagnetic subsystem and antiferromagnetic subsystem with T С =–130 K. For the samples doped with Fe by high-temperature annealing in Zn melt, few magnetic subsystems may be distinguished, however, the magnetic properties are typical for spin glasses with the transition temperature T sg =(45–50) K.

Persistent photoconductivity is observed in ZnO single crystals and ceramics together with persistence of electron paramagnetic resonance (EPR) spectra of defects and impurity centers. It is shown that when the light is switched on and off the microwave conductivity detected from absorption of the microwave field is well correlated with the dc-conductivity measured with electrical contacts applied to the sample. The microwave photoconductivity arises together with light-induced EPR spectra and persists after switching off the light. Coexistence of the conductivity and EPR spectra shows that the photoexcited electrons cannot return back to paramagnetic centers. The persistent photoconductivity in ZnO ceramics is large in comparison with the effect observed in powders prepared from the same material and in ZnO single crystals. This suggests that surface conductivity is the dominant mechanism of persistent photoconductivity in ZnO.

The compositional variation of the elastic coefficients C11 and C33 for TlGa(S1−xS2 layer mixed crystal are discussed using Brillouin scattering measurements. Clear anomalies are observed for the longitudinal phonons propagating parallel to the (001) plane (elastic coefficient C11) at xc≅0.8 and xc≅0.3 in TlInxGa1−x S2 and TlGa(S1−xSex)2, respectively. These anomalies are explained by the formation of infinite clusters. A considerable difference in the rate of change of the elastic coefficient C33 with the composition for the mixed crystals TlGa(S1−xSex) 2 and TlInxGa1−xS2 is observed. The temperature variation of C33 for a TlIn0.95Ga0.05S2 mixed crystals is also given and the results are discussed.

Size-dependent effects of microwave absorption are investigated in micron and submicron size YBaCuO powders. It is shown that the hysteresis and step-like change of field-modulated microwave absorption (FMMA) decreases when the particle size decreases. Two contributions to the relaxation of the FMMA signals were found.

Hysteretic behaviour of field-modulated microwave absorption is investigated in thin YBaCuO films with thickness d≈50 or 400 nm, by scanning the external magnetic field in opposite directions, and in constant magnetic fields when the specimen is rotated. A negative hysteresis loop of field-modulated microwave absorption is detected in the films with d≈50 nm . An addition signal corresponding to decrease of the absorption when the field is parallel to the film surface is found.

The random-exchange metallic spin-glass Ho5Co50Al45 is investigated using static magnetization measurements and scaling analysis. The results suggest that the freezing phenomenon at T f ≈14 K is a paramagnetic → spin-glass transition at T g =14.2 K with critical exponents δ=6.4 and φ=3.3.

Relaxation of the isothermoremanent magnetization M(IR) has been studed in ceramic Y-Ba-Cu-O. The value of the effective pinning energy U(eff) has been determined at different temperatures according the relationship dlnM(IR)/dlnt = - kT/U(eff). It was shown that the dependence of U(eff) on the magnetizing field H(o) can be attributed to the evolution of the trapped flux distribution (as H(o) is varied) without involving any assumptions about the dependence of the pinning barrier on the field.