G. V. Loseva

Ferromagnetism and the metal-insulator transition in the magnetic semiconductor system FexMn1−xS

The results of investigations of the structure, electrical, and magnetic properties in the system of antiferromagnetic semiconductors FexMn1−xS (0<x⩽0.5) are described. It is established that metal-insulator transitions with respect to concentration and temperature are connected with changes in the magnetic properties of the system.

Low-temperature metal-insuslator transition and magnetic properties in the VxMn1−xS disordered system

A study of the structure and electrical and magnetic properties of the VxMn1−xS disordered system is reported. The existence of a low-temperature metal-insulator transition for Fermi-glass 0.4<x<0.5 compositions in paramagnetic phase, which is accompanied by a change in the structure and magnetic properties, has been established. An analysis of the magnetic properties permits a conjecture that current carriers become delocalized in these solid solutions at the metal-insulator transition temperature to form small ferromagnetically ordered regions (ferrons).

Metal-Dielectric Transitions, Magnetism, and Electronic Structure in a System of Manganese-Doped Vanadium Sulfides

The effect of the manganese doping of vanadium monosulfide in a system of the V1−xMnxS (0<x≤0.3) solid solutions on their structure and thermal, electrical, and magnetic properties has been investigated. The metal-dielectric transitions are revealed in the studied ranges of concentrations and temperatures. These transitions are accompanied by a change in the magnetic properties. It is demonstrated that the correlation in changes of the electrical and magnetic properties of the sulfides under investigation is characteristic of the metal-dielectric transitions in strongly correlated systems.

Correlation between the magnetic and electrical properties of the (VS)x(Fe2O3)2−x oxysulfide system

The correlation between the magnetic and electrical properties of the (VS)x(Fe2O3)2−x (0.9<x<1.25) oxysulfide solid solutions has been studied. The crossover of conductivity from the semimetallic to semiconducting type is accompanied by changes in the magnetic susceptibility, which are characteristic of the transition from delocalized to localized electrons. For x=1.25, a region of the ferromagnetic ordering has been established in the temperature range 90–120 K.

Transition from the Kondo regime to long-range magnetic order in the FexV1−xS system

A study is reported on the electrical and magnetic characteristics of the FexV1−xS solid-solution system with x≤0.5. A maximum in the temperature dependence of resistivity ρ(T) characteristic of the Kondo effect has been observed for small x(x<0.01). For x>0.1, long-range magnetic order sets in in the system with TK ≈ 100 K. Near x=0.05, the Fe2+ impurity behavior crosses over to a magnetically ordered phase. The electronic properties of FexV1−xS are typical of those of strongly correlated electronic systems. Both the electrical and magnetic data imply that carrier delocalization is the strongest at x=0.4.

Magnetic phases of FexV1−x S and their electronic structure

A study has been made of the FexV1−xS solid solutions with 00.1, x-ray diffraction analysis discloses a V5S8 superstructure. Samples with x>0.1 are magnetically ordered at room temperature. The concentration dependences of resistivity and magnetization exhibit sharp peaks for x=0.1 and x=0.2, respectively. The main features of the structure and electronic properties have been qualitatively explained in terms of the three-band exciton-insulator model, and the maxima in resistivity and magnetization are assigned to the formation of localized magnetic moments with S=1, which become delocalized with increasing x.