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.

No abstract

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.

No abstract

No abstract