The transport properties of the Tm x Mn 1-x S (x 0.15) solid solutions in the temperature range of 200-600 K have been investigated. The temperatures of lattice polaron pinning accompanied by the lattice strain, condensation of the infrared modes, and thermionic emission have been determined. The change of the carrier sign with temperature has been found from the Hall coefficient data and dragging of electrons by phonons, from the thermopower data. The dependence of the magnetoresistance on the concentration, current, and voltage has been established from the I-V characteristics measured without field and in an applied magnetic field of H ¼ 8 kOe in the temperature range of 300-500 K. The functional temperature dependence of the carrier relaxation time has been determined using the impedance data. The concentration region with the magnetoimpedance sign varying with frequency and temperature has been found. The increase in the relaxation time of the induced electric polarization with increasing concentration of thulium ions has been observed. The experimental data have been interpreted in the framework of the Debye and Maxwell-Wagner models, as well as the theoretical model for the Rashba spin-orbit interaction.

To establish the existence of dipole glass in the chromium-substituted bismuth pyrostannate solid solutions, the frequency and temperature dependences of the permittivity have been measured in the temperature range of 300-750 K. The field and dynamic dependences of polarization in the temperature range of 80-550 K have been determined. Using the Raman scattering spectra, the absence of inversion center has been established. The maximum of electrical resistance has been found in the vicinity of the dipole moment freezing point. The carrier type has been determined from the thermopower data. The polarization relaxation is shown to be nonexponential. The experimental data are explained within the model of dipole glass in the αphase and the model of charged crystalline domain walls with the electronpolarization relaxation mechanism above the α-β structural transition.

The electrical properties of cation-substituted ReXMn1-XS (Re = Gd, Sm, Ho) compounds are investigated in the temperature range of 77-1200 K. A change in the type of conductivity from semiconductor to “metal” in ReXMn1-XS compounds at a critical concentration of Xc with an increase in the degree of cationic substitution is detected. The metal-dielectric concentration transition in the GdXMn1-XS system is accompanied by a decrease in the value of the specific electrical resistance by 12 orders of magnitude. For Sm0.2Mn0.8S, a sharp maximum of resistance is detected at T = 100 K, which can be caused by scattering of conduction electrons on spin fluctuations of localized electrons. The metal type of conductivity was established for Sm0.25Mn0.75S. In the HoXMn1-XS system, the Anderson transition was detected for XC = 0.3 with a decrease in the value of the specific electrical resistance by 10 orders of magnitude.

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New multifunction materials in the AgXMn1‒XS (Х = 0.05) system have been synthesized and investigated in the temperature range of 77‒500 K in magnetic fields up to 12 kOe. Near the temperature of the magnetic transition (ТN = 176 K), the anomalous behavior of the temperature dependence of magnetization has been observed and has been attributed to the formation of ferrons. An analysis of the infrared spectroscopy data and I‒V characteristics has revealed the spin-polaron subband splitting. Several conductivity channels have been found from the impedance spectra. The temperature and magnetic field dependences of the carrier relaxation time have been obtained. The magnetoresistance (−21%), magnetoimpedance (−65%), magnetothermopower (−40%), and photoconductivity effects have been detected. The majority carrier type, density, and mobility have been determined from the Hall-effect measurement data. The observed effects have been explained using a ferron model.