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We present the studies of magnetic and electrical properties of Sn1-x-ySixMnyTe mixed crystals. The magnetic susceptibility measurements revealed the presence of two types of transitions interpreted as a paramagnet-ferromagnet transition at T < 10 K due to carrier mediated Ruderman-Kittel-Kasuya-Yosida magnetic interactions and the anomaly related to the structural transition to the rhombohedral phase at T = 75 K. The presence of a well-defined magnetic hysteresis with a square shape confirms that the ferromagnetic state present in our samples is related to the homogeneous magnetic domain structure with narrow domain energy distribution. The contents of the magnetic ions determined via magnetometric methods is lower than the Mn contents determined via the energy dispersive X-ray fluorescence spectroscopy method indicating the presence of a large fraction of Mn ions being either short range coupled into small clusters like pairs, triples, or other entities or having lower total magnetic momentum than Mn in high-spin state. The magnetic exchange constant of our samples is equal to 0.25-0.3 eV indicating an increase with respect to ternary Sn1-xMnxTe. [ABSTRACT FROM AUTHOR]

We present studies of structural, electrical, and magnetic properties of Ge1-xEuxTe bulk crystals with the chemical composition, x, changing from 0.020 to 0.025. The sample synthesis leads to the formation of EuTe clusters in all our samples. Moreover, the presence of Ge1-xEuxTe spinodal decompositions with broad range of chemical contents is observed even for the sample with x = 0.020. Spinodal decompositions show the antiferromagnetic order with the Néel temperature, TN, equal to about 11 K, close to that for EuTe. The magnetic field dependence of the magnetization, M(B), is characteristic of the presence of magnetic inclusions in the samples. [ABSTRACT FROM AUTHOR]

We present the studies of structural, electrical and magnetic properties of bulk Sn1−x−y PbxCryTe mixed crystals with chemical composition 0.18 ⩽ x ⩽ 0.35 and 0.007 ⩽ y ⩽ 0.071. The magnetometric studies indicate that for the high Cr-content, y = 0.071, the alloy shows ferromagnetic alignment with the Curie temperature, TC, around 265 K. The Cr5Te8 clusters are responsible for the ferromagnetic order. At low Cr content, y = 0.01, a peak in the ac magnetic susceptibility identified as the cluster-glass-like transition is observed at a temperature about 130 K. The cluster-glass-like transition is likely due to the presence of Cr2Te3 clusters in the samples with y ≈ 0.01. The transport characterization of the samples indicated strong metallic p-type conductivity with relatively high carrier concentration, n > 1020 cm−3, and carrier mobility, μ > 150 cm2/(V s). [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the magnetotransport properties of the Ge0.743Pb0.183Mn0.074Te mixed crystal. The results of magnetization measurements indicated that the compound is a spin-glass-like diluted magnetic semiconductor with critical temperature TSG = 97.5 K. Nanoclusters in the sample are observed. Both, matrix and clusters are magnetically active. Resistivity as a function of temperature has a minimum at 30 K. Below the minimum a variable-range hopping is observed, while above the minimum a metallic-like behavior occurs. The crystal has high hole concentration, p = 6.6×1020 cm-3, temperature-independent. Magnetoresistance amplitude changes from –0.78 to 1.18% with increase of temperature. In the magnetotransport measurements we observed the anomalous Hall effect with hysteresis loops. Calculated anomalous Hall effect coeffcient, RS = 2.0 × 106 m3/C, is temperature independent. The analysis indicates the extrinsic skew scattering mechanism to be the main physical mechanism responsible for anomalous Hall effect in Ge0.743Pb0.183Mn0.074Te alloy. [ABSTRACT FROM AUTHOR]

We present the studies of Sn1-xCrxTe semimagnetic semiconductors with chemical composition x ranging from 0.004 to 0.012. The structural characterization indicates that even at low average Cr-content x ⩽ 0:012, the aggregation into micrometer size clusters appears in our samples. The magnetic properties are affected by the presence of clusters. In all our samples we observe the transition into the ordered state at temperatures between 130 and 140 K. The analysis of both static and dynamic magnetic susceptibility data indicates that the spin-glass-like state is observed in our samples. The addition of Cr to the alloy seems to shift the spin-glass-like transition from 130 K for x = 0:004 to 140 K for x = 0:012. [ABSTRACT FROM AUTHOR]

We present the experimental evidence for the presence of spinodal decomposition of the magnetic ions in the Ge1-x-yCrxEuyTe samples with chemical composition varying in the range of 0:015 ⩽ x ⩽ 0:057 and 0:003 ⩽ y ⩽ 0:042. The ferromagnetic transition at temperatures 50 ⩽ T ⩽ 57 K was observed, independent of the chemical composition. The long-range carrier mediated itinerant magnetic interactions seem to be responsible for the observed ferromagnetic order. The magnetic irreversibility with coercive field HC = 5-63 mT and the saturation magnetization MS ≈ 2-6 emu/g are found to strongly depend on the chemical composition of the alloy. [ABSTRACT FROM AUTHOR]

We present preliminary studies of magnetic properties of Ge1-xCrxTe semimagnetic semiconductors with low chromium content x < 0:026. The static and dynamic magnetometry techniques were employed for the current investigations. The obtained results showed large bifurcations between zero-field cooled and field cooled magnetization curves at temperatures lower than 50 K. The dynamic susceptibility measurements proved via frequency shifting of the peaks that the observed magnetic order at low temperatures was the spin-glass-like state caused by magnetic frustration of the system. [ABSTRACT FROM AUTHOR]

We have studied the magnetic properties of ZnO nanocrystals doped with Fe2O3 in the magnetic dopant range from 5 to 70 wt%. The nanocrystals were synthesized by wet chemical method. The detailed structural characterization was performed by means of X-ray diffraction and micro-Raman spectroscopy measurements. The results of systematic measurements of magnetic AC susceptibility as a function of temperature and frequency are presented. We observed different types of magnetic behavior. For ZnO samples doped with low content of Fe2O3, the results of low-field AC susceptibility are satisfactorily explained by superparamagnetic model including inter-particle interactions. With the increase of magnetic Fe2O3 content, the spin-glass-like behavior is observed. [ABSTRACT FROM AUTHOR]