Wyniki wyszukiwania - Biblioteka Nauki

1

Anomalous Hall Effect in Ge_{1-x-y}Pb_{x}Mn_{y}Te Composite System

100%

Podgórni A. , Kilanski L. , Dobrowolski W. , Górska M. , Domukhovski V. , Brodowska B. , Reszka A. , Kowalski B. , Slynko V. , Slynko E.

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nr 5

1180-1183

EN

The purpose of this study was to investigate the magnetotransport properties of the Ge_{0.743}Pb_{0.183}Mn_{0.074}Te mixed crystal. The results of magnetization measurements indicated that the compound is a spin-glass-like diluted magnetic semiconductor with critical temperature T_{SG}=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=6.6×10^{20} 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 coefficient, R_{S} = 2.0×10^{6} m^{3}/C, is temperature independent. The analysis indicates the extrinsic skew scattering mechanism to be the main physical mechanism responsible for anomalous Hall effect in Ge_{0.743}Pb_{0.183}Mn_{0.074}Te alloy.

2

Studies of Diluted Magnetic Semiconductor Sn_{1-x-y-z}Ge_{x}Mn_{y}Gd_{z}Te

100%

Sichkovskyi V. , Radchenko M. , Lashkarev G. , Slyn'ko V. , Slyn'ko E. , Knoff W. , Domukhovski V. , Dziawa P. , Story T.

Acta Physica Polonica A

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2009

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tom 116

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nr 5

911-912

EN

Magnetization, anomalous Hall effect, thermoelectric power, magnetoresistance, and resistivity of Sn_{1-x-y-z}Ge_{x}Mn_{y}Gd_{z}Te (x = 0.039÷0.597, y = 0.077÷0.125, z = 0.0014÷0.028) mixed crystals were studied over the temperature range 4.2-300 K. The ferromagnetic order with Curie temperature 18-24 K was revealed.

3

Features of Energy Spectrum of Pb_{1-x}Mn_xTe Doped with V

100%

Artamkin A. , Dobrovolsky A. , Dziawa P. , Story T. , Slynko E. , Slynko V. , Ryabova L. , Khokhlov D.

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tom 110

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nr 2

151-156

EN

Recently new effects that are not characteristic of undoped lead telluride, such as the Fermi level pinning, giant negative magnetoresistance, were observed in Pb_{1-x}Mn_xTe alloys doped with transition and rare earth elements - Cr, Mo, Yb. We have studied transport and magnetic properties of Pb_{1-x}Mn_xTe doped with another transition element - vanadium. A series of Pb_{1-x}Mn_xTe(V) samples of different composition and degree of doping was investigated. It was observed that the resistivity demonstrates activation behavior at low temperatures for the samples with considerable amount of vanadium as well as for the samples without vanadium. The activation energy is proportional to the Mn content. In some of the samples, photoconductivity was observed at low temperatures. The results are discussed in terms of a model assuming formation of the impurity level by the vanadium impurity and the effect of the Fermi level pinning by this level.

4

The Role of Frustration in Magnetism of Ge_{1-x}Cr_{x}Te Semimagnetic Semiconductor

100%

Kilanski L. , Górska M. , Dobrowolski W. , Arciszewska M. , Domukhovski V. , Anderson J. , Butch N. , Podgórni A. , Slynko V. , Slynko E.

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nr 5

654-656

EN

We present preliminary studies of magnetic properties of Ge_{1-x}Cr_{x}Te 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.

5

Magnetic Order and Magnetic Inhomogeneities in SnCrTe-PbCrTe Solid Solutions

80%

Kilanski L. , Szymański M. , Brodowska B. , Górska M. , Szymczak R. , Podgórni A. , Avdonin A. , Reszka A. , Kowalski B. , Domukhovski V. , Arciszewska M. , Dobrowolski W. , Slynko V. , Slynko E.

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nr 5

1203-1206

EN

We present the studies of structural, electrical and magnetic properties of bulk Sn_{1-x-y}Pb_xCr_yTe 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, T_{C}, around 265 K. The Cr_5Te_8 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 Cr_2Te_3 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 > 10^{20} cm^{-3}, and carrier mobility, μ > 150 cm^2/(V s).

6

Spinodal Decomposition of Magnetic Ions in Eu-Codoped Ge_{1-x}Cr_{x}Te

80%

Podgórni A. , Kilanski L. , Dobrowolski W. , Górska M. , Reszka A. , Domukhovski V. , Kowalski B. , Brodowska B. , Anderson J. , Butch N. , Slynko V. , Slynko E.

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nr 6

1012-1015

EN

We present the experimental evidence for the presence of spinodal decomposition of the magnetic ions in the Ge_{1-x-y}Cr_{x}Eu_{y}Te 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 H_C = 5 - 63 mT and the saturation magnetization M_S ≈ 2 - 6 emu/g are found to strongly depend on the chemical composition of the alloy.