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We present studies of the influence of the chemical composition changes on the type of magnetic order present in bulk nanocomposite Ge 1− x−y Pb x Cr y Te crystals with the average Pb-content close to x ≈ 0.20 and Cr-content, y , varying from y = 0.017 up to 0.043. Detailed magnetometric studies revealed the existence of two ordered magnetic states present in all our samples. All our crystals show a paramagnet to spin-glass-like state transition at temperatures from 135 K to 145 K, related to the presence of Cr 5 Te 8 clusters in the host lattice. The second transition type depends on the Cr-content, y . In the case of samples with y equal to 0.038 and 0.043 the ferromagnetic phase is observed with T C slightly below 70 K, while in samples with lower chromium concentration the presence of spin-glass-like state slightly below 50 K is observed. The presence of clusters in our samples has significant impact on the carrier transport and magnetotransport in our samples. The presence of critical scattering on the magnetic impurities is observed in resistivity and magnetoresistance data. Nearly-linear magnetoresistance is also observed in our samples indicating a presence of strong scattering on the grain boundaries in our samples.

We present studies of magnetotransport properties of Ge 1− x − y Pb x Mn y Te bulk crystals with chemical composition changing from 0.180 x y T SG around 90 K. The presence of strong anomalous Hall effect (AHE) with hysteresis is observed at T T SG . The data analysis allowed calculation of a correction to the Hall constant R H for T T SG and the AHE constant, R S . R S is around 10 −6 m 3 /C. R S and R H do not change strongly with temperature. The scaling law analysis has proved that the AHE in this system is due to the extrinsic mechanisms dominated by the skew scattering with relatively small contribution of the side jump process. Strong localization occurs in our system at T T SG and causes a presence of a minimum in the resistivity vs. temperature dependence. The magnetoresistance of our samples shows complex behavior at T T SG . The negative magnetoresistance is observed at T T nearly linear positive magnetoresistance is observed at temperatures from 20 K up to T ≈ T SG , where it reaches maximum. Positive linear magnetoresistance is related to the granular nature of our samples while the maximum near T SG is related to the giant spin-splitting of the valence band.

We present the studies of structural, electrical, and magnetic properties of bulk Sn 1 − x − y Cr x Eu y Te crystals with different chemical compositions varying in the range of 0.004 ≤ x ≤ 0.089 and 0.007 ≤ y ≤ 0.020. The structural characterization of our samples indicated the clustering of the Cr-ions into Cr–Te related clusters. Eu ions do not form clusters and are randomly distributed in the SnTe lattice. The magnetotransport studies show the presence of positive linear magnetoresistance with maximum amplitude of about 80% for all our samples. Positive magnetoresistance is a geometrical effect related to the presence of clusters in the SnTe lattice. The cluster-glass-like state at the temperature of about 130 K is observed for x ≤ 0.025. The cluster-glass-like state is due to the presence of Cr-rich clusters in the SnTe lattice. The ferromagnetic behavior with the Curie temperature of about 275 K is observed for the samples with x > 0.077 indicating the presence of Cr 5 Te 8 clusters in the host material. Eu ions presence in our samples shows paramagnetic behavior.

We present studies of magnetic properties of Ge 1− x − y Pb x Mn y Te bulk crystals with chemical composition varying in the range of 0.180 x y J pd , having values from 0.47 eV to 0.80 eV gives spin-glass transition temperature, T SG , values close to the experimental values for the Ge-rich phase. The magnetic order observed for the Pb-rich phase is also due to the carrier mediated magnetic interaction. The experimental transition temperatures are fitted with J pd value ranging from 0.22 eV to 0.28 eV.

Galvanomagnetic effects in diluted magnetic semiconductors Pb 1− x − y Sn x Cr y Te at temperatures 4.2≤ T ≤300 K under variation of matrix composition ( x =0.06–0.235) and impurity content ( y =0.002–0.045) have been investigated. The p–n-conversion of the conductivity type, induced by the chromium doping, was observed. It is shown that in the heavily doped alloys temperature dependencies of resistivity and of the Hall coefficient have a “metallic” character, indicating pinning of the Fermi level by the chromium deep impurity level, situated in the conduction band. Free electron concentration and Fermi energy were calculated as functions of impurity concentration and of matrix composition by analyzing experimental data in the framework of the two-band Kane dispersion law. The impurity content coefficients of the free charge carrier concentration were determined and the diagram of electronic structure rearrangement under varying the alloy composition was obtained for the alloys under study.

The galvanomagnetic properties (T=4.2―300 K, B≤0.08T) of Pb 1―x―y Sn x V y Te alloys (x=0.06-0.26, y=0.002-0.066) have been investigated. Low temperature activation range of the impurity conductivity on the temperature dependencies of resistivity p and of the Hall coefficient R H in the heavily doped samples has been revealed and attributed to the appearance of vanadium-induced deep level in the gap of the alloys. It was found that in insulating phase alloys possess a high photosensitivity to IR excitation at temperatures up to T c ≈ 40 K. In the alloy with x ≈ 0.2 the metal-insulator transition due to the shift of the Fermi level from the valence band to the gap with the increase of the vanadium and tin content and the pinning of the Fermi level by vanadium level were observed. The diagram of electronic structure reconstruction for Pb 1 ―x―y Sn x V y Te alloys was proposed.

The electronic structure of polycrystalline Ge 0.86 Mn 0.14 Te—ferromagnetic semiconductor with T C =110 K, has been studied by means of resonant photoemission spectroscopy for photon energies close to the Mn 3p→3d excitation. The contribution of Mn 3d states to the electronic structure of the system was revealed and position of the Mn ions in the crystal, characteristic of GeTe-based diluted magnetic semiconductors was proved.

In the present paper we report on results obtained by complex investigations of galvanomagnetic and magnetic properties of a diluted magnetic semiconductor Pb 1-y Yb y Te. Ytterbium doping modifies the energy spectrum of charge carriers in lead telluride by formation of deep impurity levels, moving from valence to forbidden band with increase of ytterbium content. The paramagnetic Curie-Weiss response observed has revealed a small fraction of Yb ions in magnetically active Yb 3 charge state, while the majority of impurity ions are in non-magnetic Yb 2+ state. We couple the magnetic and galvanomagnetic data in a model of charge carriers energy spectrum in Pb 1-y Yb y Te, for which energy position and electron population of the ytterbium level are derived as a function of impurity concentration.

We investigate galvanomagnetic properties and photoconductivity kinetics of Pb 1− x Ge x Te ( x ⩽0.04) alloys doped with Yb. We have found that the existence of the deep impurity level in the energy spectrum causes high photosensitivity of the alloys at temperatures under 40 K and the effect of persistent photoconductivity at helium temperature. The photoconductivity kinetics shows two types of relaxation processes: a fast one and a long-duration one. The obtained results are explained by the Jahn–Teller nature of the Yb-induced defect states. The parameters of the Jahn–Teller states are estimated.

It is expected that joint existence of ferromagnetic properties and ferroelectric structural phase transition in diluted magnetic semiconductors IV–VI leads to new possibilities of these materials. Temperature of ferroelectric transition for such crystals can be tuned by the change of Sn/Ge ratio. Magnetic susceptibility, Hall effect, resistivity and thermoelectric power of Ge 1− x − y Sn x Mn y Te single crystals grown by Bridgeman method ( x =0.083–0.115; y =0.025–0.124) were investigated within 4.2–300 K. An existence of FM ordering at T C ∼50 K probably due to indirect exchange interaction between Mn ions via degenerated hole gas was revealed. A divergence of magnetic moment temperature dependences at T ⩽ T C in field-cooled and zero-field-cooled regimes is obliged to magnetic clusters which are responsible for superparamagnetism at T > T C ≈ T f (freezing temperature) and become ferromagnetic at T C arranging spin glass state at T T f ≈ T C . Phase transition of ferroelectric type at T ≈46 K was revealed. Anomalous Hall effect which allows to determine magnetic moment was observed.