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480 results on '"Dynowska E"'

1. Chalcopyrite semimagnetic semiconductors: From nanocomposite to homogeneous material

Author

Kilanski L., Dobrowolski W., Szymczak R., Dynowska E., Wójcik M., Romčević M., Romčević N., Fedorchenko I.V., and Marenkin S.F.

Subjects
semimagnetic-semiconductors, magnetic-impurity-interactions, exchange-interactions, Chemical technology, TP1-1185
Abstract

Currently, complex ferromagnetic semiconductor systems are of significant interest due to their potential applicability in spintronics. A key feature in order to use semiconductor materials in spintronics is the presence of room temperature ferromagnetism. This feature was recently observed and is intensively studied in several Mn-alloyed II-IV-V2 group diluted magnetic semiconductor systems. The paper reviews the origin of room temperature ferromagnetism in II-IV-V2 compounds. In view of our recent reports the room temperature ferromagnetism in Mn-alloyed chalcopyrite semiconductors with more than 5 molar % of Mn is due to the presence of MnAs clusters. The solubility of magnetic impurities in bulk II-IV-V2 materials is of the order of a few percent, depending on the alloy composition. High values of the conducting hole - Mn ion exchange constant Jpd have significant value equal to 0.75 eV for Zn0.997Mn0.003GeAs2. The sample quality has significant effect on the magnetotransport of the alloy. The magnetoresistance of the alloy change main physical mechanism from spin-disorder scattering and weak localization for homogeneous samples to cluster-related geometrical effect observed for nanocomposite samples. The magnetoresistance of the II-IV-V2 alloys can be then tuned up to a few hundreds of percent via changes of the chemical composition of the alloy as well as a degree of disorder present in a material. [Projekat Ministarstva nauke Republike Srbije, br. III45003]

Published
2014
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3. Point defects and p-type conductivity in Zn/1-x/Mn/x/GeAs/2/

Author

Kilanski, L., Rauch, C., Tuomisto, F., Podgorni, A., Dynowska, E., Dobrowolski, W., Fedorchenko, I. V., and Marenkin, S. F.

Subjects
Condensed Matter - Materials Science
Abstract

Positron annihilation spectroscopy is used to study point defects in Zn/1-x/Mn/x/GeAs/2/ crystals with low Mn content 0 < x < 0.042 with disordered zincblende and chalcopyrite structure. The role of negatively charged vacancies and non-open-volume defects is discussed with respect to the high p-type conductivity with carrier concentration 1E19 < n < 1E21 cm^-3 in our samples. Neutral As vacancies, together with negatively charged Zn vacancies and non-open-volume defects with concentrations around 1E16-1E18 cm^-3, increasing with the amount of Mn in the alloy, are observed. The observed concentrations of defects are not sufficient to be responsible for the strong p-type conductivity of our crystals. Therefore, we suggest that other types of defects, such as extended defects, have a strong influence on the conductivity of Zn1-xMnxGeAs2 crystals., Comment: 8 pages, 3 figures

Published
2014
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4. Homogeneous limit of Cd(1-x)Mn(x)GeAs(2) alloy: electrical and magnetic properties

Author

Kilanski, L., Górska, M., Dynowska, E., Podgórni, A., Avdonin, A., Dobrowolski, W., Fedorchenko, I. V., and Marenkin, S. F.

Subjects
Condensed Matter - Materials Science
Abstract

We present the studies of structural, electrical, and magnetic properties of bulk Cd$_{1\textrm{-}x}$Mn$_{x}$GeAs$_{2}$ crystals with low Mn content, $x$, varying from 0 to 0.037. The studied samples have excellent crystallographic quality indicated by the presence of diffraction patterns never before observed experimentally for this compound. The electrical transport in our samples is dominated by thermal activation of conducting holes from the impurity states to the valence band with activation energy of about 200$\;$meV. The defect states acting as ionic scattering centers with concentration in the range from 6 to 15$\times$10$^{17}$$\;$cm$^{-3}$ are observed. The effective Mn content in our samples, $\bar{x}_{\theta}$, determined from fit of the susceptibility data to the Curie-Weiss law, is very close to the average chemical content, $x$. It indicates that the Mn ions are distributed randomly, substituting the Cd sites in the host CdGeAs$_{2}$ lattice. We observe a negative Curie-Weiss temperature, $|\theta|$$\,$$\leq$$\,$3.1$\;$K, increasing as a function of $x$. This indicates the significance of the short-range interactions between the Mn ions., Comment: 7 pages, 5 figures

Published
2014
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5. Low-Dilution Limit of Zn_{1-x}Mn_{x}GeAs_{2}: electrical and magnetic properties

Author

Kilanski, L., Szałowski, K., Szymczak, R., Górska, M., Dynowska, E., Aleshkevych, P., Podgórni, A., Avdonin, A., Dobrowolski, W., Fedorchenko, I. V., and Marenkin, S. F.

Subjects
Condensed Matter - Materials Science
Abstract

We present the studies of electrical transport and magnetic interactions in Zn_{1-x}Mn_{x}GeAs_{2} crystals with low Mn content 0 \leq x \leq 0.043. We show that the ionic-acceptor defects are mainly responsible for the strong p-type conductivity of our samples. We found that the negative magnetoresistance (MR) with maximum values of about -50% is related to the weak localization phenomena. The magnetic properties of Zn1-xMnxGeAs2 samples show that the random Mn-distribution in the cation sites of the host lattice occurs only for the sample with the lowest Mn-content, x=0.003. The samples with higher Mn-content show a high level of magnetic frustration. Nonzero Curie-Weiss temperature observed in all our samples indicates that weak ferromagnetic (for x=0.003) or antiferromagnetic (for x>0.005) interactions with |{\Theta}|<3 K are present in this system. The RKKY model, used to estimate the Mn-hole exchange integral Jpd for the diluted Zn/0.997/Mn/0.003/GeAs/2/ sample, makes possible to estimate the value of Jpd =(0.75+/-0.09) eV., Comment: 10 pages, 7 figures

Published
2013
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7. New evidence for structural and magnetic properties of GaAs:(Mn,Ga)As granular layers

Author

Bak-Misiuk, J., Lawniczak-Jablonska, K., Dynowska, E., Romanowski, P., Domagala, J. Z., Libera, J., Wolska, A., Klepka, M. T., Dluzewski, P., Sadowski, J., Barcz, A., Wasik, D., Twardowski, A., Kwiatkowski, A., and Caliebe, W.

Subjects
Condensed Matter - Materials Science, J.2
Abstract

Structural and magnetic properties of GaAs thin films with embedded MnAs nanoclusters were investigated as function of the annealing temperature and layers composition. The presence of two kinds of nanoclusters with different dimensions and structure were detected. The fraction of Mn atoms in each kind of cluster was estimated from the extended X-ray absorption fine structure analysis. This analysis ruled out the possibility of the existence of nanoclusters containing a hypothetic MnAs cubic compound - only (Mn,Ga)As cubic clusters were detected. Change of the layer strain from the compressive to tensile was related to the fraction of zinc blende and hexagonal inclusions. Thus the zinc blende inclusions introduce much larger strain than hexagonal ones. The explanation of observed thermal induced strain changes of the layers from the compressive to tensile is proposed. The magnetic properties of the samples were consistent with structural study results. Their showed that in sample containing solely cubic (Mn,Ga)As inclusions Mn ions inside the inclusions are still ferromagnetically coupled, even at room temperature. This fact can be explained by existence in these clusters of GaMnAs solid solution with content of Mn higher than 15 % as was found in theoretical calculations., Comment: 12 pages, 16 figures, 4 tables

Published
2010

20. Damage in solids irradiated by a single shot of XUV free-electron laser: Irreversible changes investigated using X-ray microdiffraction, atomic force microscopy and Nomarski optical microscopy

Author

Pelka, J.B., Sobierajski, R., Klinger, D., Paszkowicz, W., Krzywinski, J., Jurek, M., Zymierska, D., Wawro, A., Petroutchik, A., Juha, L., Hajkova, V., Cihelka, J., Chalupsky, J., Burian, T., Vysin, L., Toleikis, S., Sokolowski-Tinten, K., Stojanovic, N., Zastrau, U., London, R., Hau-Riege, S., Riekel, C., Davies, R., Burghammer, M., Dynowska, E., Szuszkiewicz, W., Caliebe, W., and Nietubyc, R.

Published
2009
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30. Structure of Magnetically Ordered Si:Mn

Author

Bak-Misiuk, Jadwiga, primary, Dynowska, E., additional, Romanowski, P., additional, Shalimov, A., additional, Misiuk, Andrzej, additional, Kret, S., additional, Dluzewski, P., additional, Domagala, J., additional, Caliebe, Wolfgang, additional, Dabrowski, J., additional, and Prujszczyk, M., additional

Published
2007
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31. Amorphous state and pulsed laser deposition of YBa(sub 2)Cu(sub 3)O(sub 7-delta) thin films

Author

Okunev, V.D., Samoilenko, Z.A., Svistunov, V.M., Abal'oshev, A., Dynowska, E., Gierlowski, P., Kilmov, A., and Lewandowski, S.J.

Subjects
Crystals -- Research, Thin films -- Research, Physics
Abstract

A study was conducted to analyze the structure of amorphous and crystalline YbaCuO films determined in on-axis and off-axis deposition geometries. The crystalline films were predominantly (001) oriented. Experimental results indicated the existence of amorphous continuum of spatially disordered atoms and crystalline clusters supporting quasi-two dimensional or long range orders. Findings also showed that the off-axis films supported a periodic repetition of the elements of atomic order or disorder along the direction of the plasma plume.

Published
1999

36. Fabrication and properties of YBa2Cu3O7/RE1-xAxMnO3-y multilayers

Author

Przyslupski, P., Kolesnik, S., Dynowska, E., Skoskiewicz, T., and Sawicki, M.

Subjects
Thin films, Multilayered -- Research, Crystals -- Growth, Crystal lattices -- Research, Business, Electronics, Electronics and electrical industries
Abstract

(YBa2Cu3O7-/Nd0.67Sr0.33MnO3-y)n superlattices were developed using the high-pressure direct current sputtering technique. X-ray analyses reveal that the LaAlO3 (100) substrates exhibit c-axis epitaxial growth. Lattice parameter discrepancies between the substrate and YBa2Cu3O7 sublayers strained the Nd0.67SrO.33MnO3-y films which exhibited ferromagnetic order less than 200 K.

Published
1997

40. On defects role in enhanced perpendicular magnetic anisotropy in Pt/Co/Pt, induced by ion irradiation

Author

Jakubowski, M. M., (0000-0001-7933-7295) Liedke, M. O., Butterling, M., Dynowska, E., Sveklo, I., Milińska, E., Kurant, Z., Böttger, R., Borany, J., Maziewski, A., Wagner, A., Wawro, A., Jakubowski, M. M., (0000-0001-7933-7295) Liedke, M. O., Butterling, M., Dynowska, E., Sveklo, I., Milińska, E., Kurant, Z., Böttger, R., Borany, J., Maziewski, A., Wagner, A., and Wawro, A.

Abstract

Modifications of magnetic and magneto-optical properties of Pt/Co(dCo)/Pt upon Ar+ irradiation (with energy 1.2, 5 and 30 keV) and fluence, F at the range from 2e13-2e16 Ar+/cm^2) were studied. Two ‘branches’ of increased perpendicular magnetic anisotropy (PMA) and enhanced magneto-optical response are found on two-dimensional (dCo, F) diagrams. The difference in F between ‘branches’ is driven by ion energy. Structural features correlated with magnetic properties have been analysed thoroughly by X-ray diffraction, Rutherford backscattering spectrometry and positron annihilation spectroscopy. Experimental results are in agreement with TRIDYN numerical calculations of irradiation-induced layers intermixing. Our work discusses particularly structural factors related to crystal lattice defects and strain, created and modified by irradiation, co-responsible for the increase in PMA.

Published
2019

44. Modification of structural and magnetic properties in Fe/Pt (111)-oriented multilayers with ion beam irradiation

Author

Marynowska, A., Misiuna, P., Lewińska, S., Dynowska, E., Wawro, A., Ślawska-Waniewska, A., Böttger, R., Fassbender, J., and Baczewski, L. T.

Subjects
Magnetic and structural properties, Multilayers, Ion irradiation, Magnetic metallic thin films
Abstract

This paper reports on structural and magnetic properties changes that occur after irradiation of Fe/Pt (1 1 1) multilayers with Ne+ ions. Multilayer samples of Al2O3 (0 0 0 1)/Pt 100 Å/(Fe X Å/Pt X Å)n/Pt 100 Å structure with different individual layer thickness X (5 or 10 Å) and different number of bilayers n (5, 10 or 15) were irradiated with Ne+ ions of 10 to 25 keV energy and 1 × 1014 ÷ 1 × 1016 ions cm−2 dose range at room temperature. Irradiation parameters were estimated a priori using Tridyn software. As-deposited samples revealed presence of sharp interfaces. Structural properties changes were investigated using symmetrical and asymmetrical X-ray diffraction methods and magnetic properties changes were examined using vibrating sample magnetometer. Ion beam induced mixing of multilayers resulted in formation of disordered face centered cubic (fcc) FePt alloys of two different compositions (quasi-50:50 in the initial multilayer volume and Pt-rich in initial cover-layer volume). Non-regular changes in magnetic properties after ion irradiation were observed whilst retaining in-plane orientation of magnetization easy axis.

Published
2018

49. Point defects and p-type conductivity in Zn1-xMnxGeAs2.

Author

Kilanski, L., Rauch, C., Tuomisto, F., Podgórni, A., Dynowska, E., Dobrowolski, W., Fedorchenko, I. V., and Marenkin, S. F.

Subjects
POSITRON annihilation, POINT defects, DISLOCATIONS in crystals, CRYSTAL defects, ANNIHILATION reactions, CHALCOPYRITE
Abstract

Positron annihilation spectroscopy is used to study point defects in Zn1-xMnxGeAs2 crystals with low Mn content 0 ≤ χ ≤ 0:042 with disordered zincblende and chalcopyrite structure. The role of negatively charged vacancies and non-open-volume defects is discussed with respect to the high p-type conductivity with carrier concentration 1019 ≤ p ≤ 1021 cm-3 in our samples. Neutral As vacancies, together with negatively charged Zn vacancies and non-open-volume defects with concentrations around 1016 - 1018 cm-3, are observed to increase with increasing Mn content in the alloy. The observed concentrations of defects are not sufficient to be responsible for the strong p-type conductivity of our crystals. Therefore, we suggest that other types of defects, such as extended defects, have a strong influence on the conductivity of Zn1-xMnxGeAs2 crystals. [ABSTRACT FROM AUTHOR]

Published
2014
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50. Homogeneous limit of Cd1-xMnxGeAs2 alloy: Electrical and magnetic properties.

Author

Kilanski, L., Górska, M., Dynowska, E., Podgórni, A., Avdonin, A., Dobrowolski, W., Fedorchenko, I. V., and Marenkin, S. F.

Subjects
MAGNETIC properties, METHACRYLONITRILE, OPTICAL diffraction, PROPERTIES of matter, ELECTRONS
Abstract

We present the studies of structural, electrical, and magnetic properties of bulk Cd1-xMnxGeAs2 crystals with low Mn content, x, varying from 0 to 0.037. The studied samples have excellent crystallographic quality indicated by the presence of diffraction patterns never before observed experimentally for this compound. The electrical transport in our samples is dominated by thermal activation of conducting holes from the impurity states to the valence band with activation energy of about 200 meV. The defect states acting as ionic scattering centers with concentration in the range from 6 to 15 × 1017 cm-3 are observed. The effective Mn content in our samples, xθ, determined from fit of the susceptibility data to the Curie-Weiss law, is very close to the average chemical content, x. It indicates that the Mn ions are distributed randomly, substituting the Cd sites in the host CdGeAs2 lattice. We observe a negative Curie-Weiss temperature, ∣θ∣ ⩽ 3:1K, increasing as a function of x. This indicates the significance of the short-range interactions between the Mn ions. © 2014 AIP Publishing LLC. [ABSTRACT FROM AUTHOR]

Published
2014
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