Search results

1

Preparation and Optical Properties of Zn_{1-x}Mn_xTe_{1-y}O_y Highly Mismatched Alloy

100%

Avdonin A., Van Khoi L., Pacuski W., Domukhovski V., Gałązka R.

Acta Physica Polonica A

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2007

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vol. 112

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issue 2

407-414

EN

The Zn_{1-x}Mn_xTe_{1-y}O_y alloy was prepared using a rapid crystallization technique. X-ray diffraction measurements were used to estimate the oxygen doping level. It is demonstrated that the oxygen solubility in Zn_{1-x} Mn_xTe_{1-y}O_y alloys greatly depends on the manganese concentration. No oxygen related effects were observed in the manganese free samples. The highest value of the oxygen molar fraction (y) achieved in the present study was 0.0023 in a sample having manganese fraction (x) of 0.056. The decrease in the alloy band gap was observed with increasing oxygen content. The oxygen-related trap level in Zn_{1-x}Mn_xTe_{1-y}O_y was found to be strongly shifted with respect to that in ZnTe_{1-y}O_y. The shift is assigned to a creation of complex (Mn_xO) traps.

2

Strain Relaxation in Thin Films of La_{1.85}Sr_{0.15}CuO_4 Grown by Pulsed Laser Deposition

87%

Zaytseva I., Cieplak M., Abal'oshev A., Berkowski M., Domukhovski V., Paszkowicz W., Shalimov A.

Acta Physica Polonica A

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2007

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vol. 111

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issue 1

185-188

EN

X-ray diffraction, resistivity, and susceptibility measurements are used to examine the effects of film thickness d (from 17 to 250 nm) on the structural and superconducting properties of La_{1.85}Sr_{0.15}CuO_4 films grown by pulsed laser deposition on SrLaAlO_4 substrates. For each d the film sgrow with a variable strain, ranging from a large compressive strain in the thinnest films to a negligible or tensile strain in thick films. Our results indicate that the tensile strain is not caused by the off-stoichiometric layer at the substrate-film interface. Instead, it may be caused by the extreme oxygen deficiency in some of the films.

3

Effect of the In-Plane Epitaxial Mismatch between the Substrate and the Film on the Properties of YBa_2Cu_3O_{7-δ} Films

87%

Abal'osheva I., Cieplak M., Adamus Z., Berkowski M., Domukhovski V., Aleszkiewicz M.

Acta Physica Polonica A

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2006

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vol. 109

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issue 4-5

549-554

EN

We study the effect of the in-plane epitaxial mismatch between the substrate and the film on the crystallographic structure and the transport properties of YBa_2Cu_3O_{7-δ} superconducting films of thicknesses ranging between 600 and 3000Å. The films are grown by pulsed laser deposition on the new type of single-crystalline substrates prepared by Czochralski method, with the chemical formula (SrAl_{0.5}Ta_{0.5}O_3)_{0.7}(CaAl_{0.5}Ta_{0.5}O_3)_{0 .1}(LaAlO_3)_{0.2}. We find that superconducting properties of the samples are excellent, and generally they improve with increasing of the film thickness as a result of improved structural ordering. We also investigate the influence of the film thickness on the behavior of the critical current densities.

4

Substrates Grown from the Vapor for ZnO Homoepitaxy

87%

Skupiński P., Kopalko K., Łusakowska E., Domukhovski V., Jakieła R., Mycielski A., Grasza K.

Acta Physica Polonica A

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2008

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vol. 114

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issue 5

1361-1368

EN

The novel method of preparation of epi-ready ZnO substrates is demonstrated. The substrates were made of unique ZnO crystals grown by chemical vapor transport method using hydrogen as the transport agent. The effect of low-level doping (Mn, Co, Cu, and V) on the structural quality of the crystals was investigated. Atomic layer deposition was used to verify usability of the substrates for homoepitaxy. The thermal annealing prior to the atomic layer deposition process and effect of thermal annealing of the epitaxial layers was studied. The X-ray diffraction and atomic force microscopy methods were applied to study the structural quality of the ZnO layers. Detection of the dopants in the substrates by secondary ion mass spectroscopy made possible the measurement of the thickness of the layers. The obtained root mean square roughness for both the substrates and layers ranged between 0.2 nm and 5 nm, and was dependent on the sample crystallographic orientation and sequence of polishing and annealing procedures. The optimal recipe for the epi-ready substrate preparation was formulated.

5

Structure and Superconductivity of FeSe_{1 - x} and FeTe_{1 - y}Se_{y} Crystals: Dependence on the Synthesis Methods, Starting Composition, and Growth Conditions

87%

Gawryluk D., Fink-Finowicki J., Wiśniewski A., Puźniak R., Domukhovski V., Diduszko R., Berkowski M.

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issue 2

331-335

EN

Syntheses of superconducting iron chalcogenides FeSe_{1 - x} (x = 0-0.15) and FeTe_{1 - y}Se_{y} (y = 0.3-0.55) were performed. Superconducting phase of iron selenide was obtained by the solid-state reaction and from liquid phase. The highest values of critical temperature (T_c = 8.2-8.7 K) exhibit FeSe_{1-x} obtained by the crystallization from a melt with excess of iron less than 1 mol%. The samples from a melt contain up to 78% of tetragonal phase, as estimated by the X-ray diffraction. Lattice parameters and unit cell volume for the samples exhibiting highest T_{c} and sharpest transition to superconducting state are limited to narrow range, with c/a ratio close to 1.469. The samples with excess of selenium contain higher amount of hexagonal phase than stoichiometric one. Superconducting single-crystalline samples of FeTe_{1 - y}Se_{y} (up to 100% of tetragonal phase) were obtained using Bridgman's method. When y value increases, the volume of unit cell decreases. The critical temperature T_{c} changes from ≈ 11.5 K for y ≈ 0.3 to ≈ 14.7 K for y ≈ 0.5.

6

AC Magnetic Susceptibility Studies of Ge_{1-x-y}Sn_{x}Mn_{y}Te Mixed Crystals

87%

Kilanski L., Arciszewska M., Domukhovski V., Dobrowolski W., Slynko V., Slynko I.

Acta Physica Polonica A

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2008

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vol. 114

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issue 5

1145-1150

EN

We present preliminary studies of magnetic and transport properties of Ge_{1-x-y}Sn_xMn_yTe mixed crystals with 0.091 ≤ x ≤ 0.105 and 0.012 ≤ y ≤ 0.115. Qualitative analysis of our experimental results showed the appearance of a spin-glass phase at T < 50 K. The transport characterization (resistivity and Hall effect measurements) showed that the investigated samples had semimetallic p-type conductivity with relatively large carrier concentrations (p > 10^{21} cm^{-3}) and low mobilities (μ < 100 cm^2 V^{-1} s^{-1}). The dependence of transport properties on the chemical composition of the samples was observed.

7

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

73%

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

Acta Physica Polonica A

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2011

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vol. 119

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issue 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.

8

The Role of Frustration in Magnetism of Ge_{1-x}Cr_{x}Te Semimagnetic Semiconductor Acta Physica Polonica A 119, 654 (2011), ERRATUM

73%

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

Acta Physica Polonica A

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2011

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vol. 119

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issue 6

904

9

Magnetic Properties of FeSeTe Compound Crystallized from Liquid Phase

73%

Lewandowski S., Berkowski M., Tarenkov V., D'yachenko A., Abal'oshev A., Abal'osheva I., Gawryluk D., Domukhovski V., Sidorov S., Boichenko D.

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issue 2

289-291

EN

We report on measurements of samples with nominal composition FeSe_{0.5}Te_{0.5}, crystallized by the Bridgman method. Magnetic and transport properties of the samples were examined. The measurements confirm the coexistence of ferromagnetism and superconductivity below the superconducting transition temperature. The ferromagnetic contribution to magnetization, estimated at 10%, might be caused by the presence of ferrimagnetic Fe_7Se_8, which occupies about 10% of sample volume. From the Andreev spectroscopy we found superconducting energy gap Δ = 2.6 meV at T = 4.2 K, and from magnetization measurements the critical temperature T_c = 15.8 K. The critical current density in magnetic field H = 4 kOe, determined from magnetization measurements, is j_c = (1-2) × 10^4 A/cm^2 and weakly depends on magnetic field intensity.

10

Magnetic Properties of EuS/Co Multilayers on KCl and BaF₂ Substrates

73%

Szot M., Kowalczyk L., Story T., Domukhovski V., Knoff W., Gas K., Volobuev V., Sipatov A., Fedorov A.

Acta Physica Polonica A

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2008

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vol. 114

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issue 5

1397-1402

EN

Magnetic and structural properties of EuS/Co multilayers were studied by magnetic optical Kerr effect and SQUID magnetometry techniques and by X-ray diffraction method. The multilayers containing monocrystalline, ferromagnetic EuS layer (thickness 35-55 Å) and metallic Co layer (thickness 40-250 Å), were grown on KCl (001) and BaF₂ (111) substrates using high vacuum deposition technique employing electron guns for Co and EuS. All investigated EuS/Co multilayers exhibit ferromagnetic properties at room temperature due to Co layer with the ferromagnetic transition in EuS layer clearly marked upon cooling below 16 K. In EuS/Co/EuS trilayers grown on KCl substrate the antiferromagnetic alignment of magnetization vectors of Co and EuS layers was experimentally observed as a characteristic low field plateau on magnetization hysteresis loops and a decrease in multilayer magnetization below 16 K. In Co/EuS bilayers the characteristic temperature dependent shift of magnetization loops was found due to exchange bias effect attributed to the CoO/Co interface formed by the oxidation of the top Co layer.

11

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

73%

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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vol. 116

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issue 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.

12

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

73%

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

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vol. 126

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issue 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.

13

Zn_{1-x}(Mn,Co)_xGeAs_2 Ferromagnetic Semiconductor: Magnetic and Transport Properties

73%

Kilanski L., Gorska M., Domukhovski V., Dobrowolski W., Anderson J., Rotundu C., Varniavskii S., Marenkin S.

Acta Physica Polonica A

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2008

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vol. 114

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issue 5

1151-1157

EN

We present the studies of magnetic and transport properties of the bulk Zn_{1-x}(Mn, Co)_xGeAs_2 mixed crystals with 0.052 ≤ x ≤0.182 grown using direct fusion method. Magnetic investigations showed that for samples with x ≥ 0.078 we observed a behavior typical of ferromagnets, with the Curie temperatures T_C ≥ 300 K. The observed ferromagnetism was probably connected with the spinodal decomposition of the Mn ions in the alloy. The transport studies including resistivity and Hall effect (at B=1.4 T) were performed. The samples showed p-type conductivity with semiconducting or metallic character, depending on the alloy composition. The Hall carrier concentration, p ≥ 10^{18} cm^{-3}, was composition dependent.

14

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

60%

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

Acta Physica Polonica A

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2012

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vol. 122

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issue 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.

15

Experimental and Theoretical Analysis οf PbTe-CdTe Solid Solution Grown by Physical Vapour Transport Method

60%

Szot M., Szczerbakow A., Dybko K., Kowalczyk L., Smajek E., Domukhovski V., Łusakowska E., Dziawa P., Mycielski A., Story T., Bukała M., Galicka M., Sankowski P., Buczko R., Kacman P.

Acta Physica Polonica A

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2009

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vol. 116

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issue 5

959-961

EN

Bulk monocrystals of Pb_{1-x}Cd_{x}Te, with the Cd content x up to 0.11, were grown by physical vapour transport method. The structural, electrical and optical properties of these ternary crystals were studied experimentally and theoretically. All investigated samples exhibit rock-salt structure and high crystal quality, which was confirmed by X-ray rocking curve width parameter of about 100 arcsec. The decrease of the lattice parameter with increasing Cd content x was found experimentally, in agreement with ab initio calculations. The band structures of Pb_{1-x}Cd_{x}Te mixed crystals for x values up to 0.2 were calculated using tight binding approach. The calculated band gap in the L-point increases with the Cd content in qualitative agreement with photoluminescence measurements in the infrared. For all studied Pb_{1-x}Cd_{x}Te samples, the Hall effect and electrical conductivity measurements, performed in the temperature range from 4 to 300 K, revealed p-type conductivity.

16

Magnetic and Structural Properties of EuS-PbS Multilayers Grown on n-PbS (100) Substrates

60%

Chernyshova M., Łusakowska E., Domukhovski V., Grasza K., Szczerbakow A., Wrotek S., Kowalczyk L., Story T., Smits C., Swagten H., De Jonge W., Palosz W., Sipatov A., Volobuev V.

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issue 4-5

609-615

EN

Magnetic properties of semiconductor EuS(t)-PbS(d)-EuS(t) ferromagnetic trilayers (t=30÷300Å and d=7.5÷70Å) grown on n-type monocrystalline PbS (100) substrate were studied by SQUID magnetometry and ferromagnetic resonance technique yielding, in particular, the dependence of the ferromagnetic Curie temperature on the thickness of the EuS layer. Structural parameters of layers were examined by X-ray powder diffraction analysis. A high structural quality of the substrate and the multilayer was verified by the measurements of the X-ray rocking curve width indicating the values of the order of 100 arcsec and by atomic force microscopy revealing the presence on the cleft PbS surface regions practically flat in the atomic scale over the area of 1×0.1μm^2.

17

Magnetic Order and Magnetic Inhomogeneities in SnCrTe-PbCrTe Solid Solutions

60%

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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vol. 126

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issue 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).

18

Ferromagnetic Transition in Ge_{1-x}Mn_{x}Te Layers

60%

Knoff W., Domukhovski V., Dybko K., Dziawa P., Jakieła R., Łusakowska E., Reszka A., Świątek K., Taliashvili B., Story T., Szałowski K., Balcerzak T.

Acta Physica Polonica A

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2009

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vol. 116

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issue 5

904-906

EN

Ferromagnetic transition temperature in thin layers of diluted magnetic (semimagnetic) semiconductor Ge_{1-x}Mn_{x}Te was studied experimentally by SQUID magnetometry method and analyzed theoretically for a model Ising-type diluted magnetic system with Ruderman-Kittel-Kasuya-Yosida indirect exchange interaction. The key features of the experimentally observed dependence of the Curie temperature on Mn content (x ≤ 0.12) and conducting hole concentration p = (1-10) × 10^{21} cm^{-3} were reproduced theoretically for realistic valence band and crystal lattice parameters of p-Ge_{1-x}Mn_{x}Te taking into account short carrier mean free path encountered in this material and Ruderman-Kittel-Kasuya-Yosida mechanism with both delta-like and diffused character of spatial dependence of the exchange coupling between magnetic ions and free carriers.

19

Epitaxial Growth and Optical Properties of PbTe/CdTe Semiconductor Heterostructures

60%

Szot M., Kowalczyk L., Smajek E., Domukhovski V., Domagała J., Łusakowska E., Taliashvili B., Dziawa P., Knoff W., Wiater M., Wojtowicz T., Story T.

Acta Physica Polonica A

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2008

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vol. 114

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issue 5

1391-1396

EN

Growth optimization, optical and structural properties of PbTe/CdTe multilayers grown by molecular beam epitaxy on GaAs (001) as well as on BaF_2 (111) substrates is reported. An intense photoluminescence in the mid-infrared region is observed from PbTe quantum wells excited with 1.17 eV pulsed YAG:Nd laser. The energy of the emission peak shows blue shift with decreasing PbTe well width and has a positive temperature coefficient. The influence of thermal annealing on photoluminescence spectra of PbTe/CdTe multilayers grown on BaF_2 substrate is discussed.

20

Magnetic Properties of Epitaxial (Ge,Mn)Te Thin Films with Varying Crystal Stoichiometry

60%

Knoff W., Domukhovski V., Dybko K., Dziawa P., Górska M., Jakieła R., Łusakowska E., Taliashvili B., Story T., Reszka A., Anderson J., Rotundu C.

Acta Physica Polonica A

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2008

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vol. 114

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issue 5

1159-1165

EN

Magnetization of 1 μm thick ferromagnetic IV-VI (Ge, Mn)Te semiconductor layers with 10 at.% of Mn was studied by SQUID magnetometry method up to the magnetic fields of 70 kOe. The layers were grown on BaF₂ (111) substrates by molecular beam epitaxy with varying Te molecular flux, which permitted the control of layer stoichiometry and conducting hole concentration. X-ray diffraction and in situ electron diffraction characterization of layer growth and crystal structure revealed two-dimensional mode of growth and monocrystalline rhombohedral crystal structure of (Ge, Mn)Te layers. Controlling the layer stoichiometry influences the temperature dependence of magnetization with the ferromagnetic Curie temperature varying in Ge_{0.9}Mn_{0.1}Te layers from T_c=30 K (low Te flux) to T_c=42 K (high Te flux).

Refine search results

Preparation and Optical Properties of Zn_{1-x}Mn_xTe_{1-y}O_y Highly Mismatched Alloy

Strain Relaxation in Thin Films of La_{1.85}Sr_{0.15}CuO_4 Grown by Pulsed Laser Deposition

Effect of the In-Plane Epitaxial Mismatch between the Substrate and the Film on the Properties of YBa_2Cu_3O_{7-δ} Films

Substrates Grown from the Vapor for ZnO Homoepitaxy

Structure and Superconductivity of FeSe_{1 - x} and FeTe_{1 - y}Se_{y} Crystals: Dependence on the Synthesis Methods, Starting Composition, and Growth Conditions

AC Magnetic Susceptibility Studies of Ge_{1-x-y}Sn_{x}Mn_{y}Te Mixed Crystals

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

The Role of Frustration in Magnetism of Ge_{1-x}Cr_{x}Te Semimagnetic Semiconductor Acta Physica Polonica A 119, 654 (2011), ERRATUM

Magnetic Properties of FeSeTe Compound Crystallized from Liquid Phase

Magnetic Properties of EuS/Co Multilayers on KCl and BaF₂ Substrates

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

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

Zn_{1-x}(Mn,Co)_xGeAs_2 Ferromagnetic Semiconductor: Magnetic and Transport Properties

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

Experimental and Theoretical Analysis οf PbTe-CdTe Solid Solution Grown by Physical Vapour Transport Method

Magnetic and Structural Properties of EuS-PbS Multilayers Grown on n-PbS (100) Substrates

Magnetic Order and Magnetic Inhomogeneities in SnCrTe-PbCrTe Solid Solutions

Ferromagnetic Transition in Ge_{1-x}Mn_{x}Te Layers

Epitaxial Growth and Optical Properties of PbTe/CdTe Semiconductor Heterostructures

Magnetic Properties of Epitaxial (Ge,Mn)Te Thin Films with Varying Crystal Stoichiometry