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1
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Scanning Tunneling Spectroscopy Sensitive to Layer Structure of BSCCO

100%
Aleszkiewicz M., Aleszkiewicz P., Raułuszkiewicz J.
Acta Physica Polonica A
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1997
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vol. 91
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issue 3
597-604
EN
Scanning tunneling microscopy images and scanning tunneling spectroscopy characteristics were measured at 4.2 K in liquid helium bath on the cleaved in air a-b surface of Bi_{2}Sr_{2}CaCu_{2}O_{8} (BSCCO-2212). Electronic densities of states and superconductivity parameters Δ and Γ evaluated from dI/dV characteristics depend on tip-sample distance s: with shortening of the distance s superconducting gap structure becomes more distinct, i.e. Δ increases and Γ decreases. We explain this phenomenon as a non-vacuum tunneling, where for longer s tunneling electrons reach only the surface contamination layer on non-metallic BiO top-surface layer, whereas for shorter s tunneling electrons penetrate also deeper lying CuO layers reflecting their superconducting properties. The dependence of Δ on s is evaluated. This result allows to understand better the non-vacuum scanning tunneling microscopy imaging: by adjusting properly the tip-sample distance one can select suitable local density of states contributing dominantly to the scanning tunneling microscopy images taken on BSCCO.
2
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Phase Diagram and Activation Energy for Vortex Pinning in Nb/(Co,Pd) Superconductor-Ferromagnet Bilayer

88%
Syryanyy Y., Aleszkiewicz M., Cieplak M., Zhu L., Chien C.
Acta Physica Polonica A
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2014
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vol. 126
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issue 4a
A-123-A-127
EN
Using the magnetoresistance measurements we study the phase transition line and the activation energy for vortex pinning in superconductor/ferromagnet bilayer, built of a ferromagnetic Co/Pd multilayer with perpendicular magnetic anisotropy, and a niobium film, with insulating layer in-between to eliminate proximity effect. The domain width is reversibly pre-defined using the angle-dependent demagnetization. We find that the enhancement of the activation energy for vortex pinning by magnetic domains is rather modest, by a factor of about 2.1. We attribute this to large domain width, and large dispersion of the domain width in this bilayer.
3
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The Effect of Surface Preparation on Physical Properties of Ni-ZnSe Junctions

88%
Chusnutdinow S., Makhniy V., Aleszkiewicz M., Zaleszczyk W., Slotov M.
Acta Physica Polonica A
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2014
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vol. 126
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issue 5
1076-1078
EN
We report on optical and photovoltaic properties of Ni-ZnSe junctions. We demonstrate that the preparation method of the ZnSe surface determines luminescence, optical transmission of ZnSe substrates and photovoltaic spectra of the Ni-ZnSe junctions. The observed effects are explained by formation of low-dimensional quantum structures on the ZnSe surface in result of the surface preparation procedure. This is confirmed by atomic force microscopy studies, which show the presence of grains with lateral dimensions of 30-300 nm on ZnSe surface. The smallest grains are responsible for a wide spectral band observed in photoluminescence at 3.4 eV, i.e., at much higher energies than the energy gap of bulk ZnSe, E_{g} ≈ 2.7 eV.
4
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Fabrication and Ferroelectric Properties of BiFeO₃/BaTiO₃ Heterostructures

88%
Aleszkiewicz M., Dybko K., Dynowska E., Dluzewski P., Przyslupski P.
Acta Physica Polonica A
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2016
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vol. 130
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issue 2
511-515
EN
We report on preparation and electrical characterization of the epitaxial BaTiO₃ (BTO), BiFeO₃ (BFO) thin films and BFO/BTO bi- and multilayers, grown on (001) SrTiO₃ (STO) and (LaAlO₃)_{0.3}(Sr₂TaAlO₆)_{0.7} (LSAT) substrates. The ferroelectric properties were characterized using the electric force microscopy method to image and switch the electric domains. This fabrication process opens the routes towards wide study of magnetoelectric effect in complex oxide heterostructures.
5
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STM/AFM Observations of Co/Cu Magnetic Multilayers

76%
Aleszkiewicz M., Kalinowski R., Czajka R., Polewska W., Wawro A., Baczewski L. T., Raułuszkiewicz J.
Acta Physica Polonica A
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1997
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vol. 91
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issue 2
311-314
EN
UHV deposited magnetic Co/Cu multilayers were investigated by means of scanning tunneling microscopy (STM) and atomic force microscopy (AFM). Surface of the sample i.e. upper covering layer in "plane" configuration and individual sublayers in "cross-section" configuration were investigated. A possibility of structure characterization of metallic multilayers by STM and AFM in the cross-section configuration is demonstrated.
6
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Content available

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

76%
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.
7
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Mechanical and Electrical Properties, of ZnO-Nanowire/Si-Substrate Junctions Studied by Scanning Probe Microscopy

76%
Aleszkiewicz M., Fronc K., Wróbel J., Klepka M., Wojtowicz T., Karczewski G.
Acta Physica Polonica A
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2007
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vol. 112
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issue 2
255-260
EN
Scanning tunneling spectroscopy was used to check the tunneling I-V characteristics of junctions formed by n-ZnO nanowires deposited on Si substrates with n- and p-type electrical conductivity (i.e. n-ZnO nanowire/n-Si and n-ZnO nanowire/p-Si junctions, respectively). Simultaneously, several phenomena which influence the measured I-V spectra were studied by atomic force microscopy. These influencing factors are: the deposition density of the nanowires, the possibility of surface modification by tip movement (difference in attraction forces between nanowires and the p-Si and n-Si) and the aging of the surface.
8
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Growth and Characterization of YBa_2Cu_3O_{7-δ} Films Deposited by Laser Ablation on CeO_2-Buffered Sapphire

64%
Abal'osheva I., Zaytseva I., Aleszkiewicz M., Malinowski A., Bezusyy V., Syryanyy Y., Gierłowski P., Abal'oshev O., Kończykowski M., Cieplak M.
Acta Physica Polonica A
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2014
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vol. 126
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issue 4a
A-69-A-73
EN
In this work we study the growth, by pulsed laser deposition, of YBa_2Cu_3O_{7-δ} (YBCO) films on the CeO_2-buffered R-cut sapphire substrates, with the buffer layer recrystallized prior to the deposition of superconductor. We find that the superconducting critical temperature and the critical current density of the films are very close to similar parameters for the YBCO films grown on lattice-matched single crystalline substrates. It appears that the structural defects in the buffer layer affect the microstructure of YBCO films, resulting in high values of the critical current density, suitable for applications.
9
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Content available

Topographical, Magnetic and Optical Studies of (II,Mn)VI Quantum Structures Grown on (Ga,Mn)As

64%
Butkutė R., Aleszkiewicz M., Janik E., Cywiński G., Wojnar P., Däweritz L., Primus J., De Boeck J., Kossut J.
Acta Physica Polonica A
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2003
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vol. 103
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issue 6
649-657
EN
We report on an overgrowth of quantum structures consisting of diluted magnetic semiconductor CdMnTe quantum wells with non-magnetic barriers made of CdMgTe or ZnTe on ferromagnetic MnAs and GaMnAs films by molecular beam epitaxy. Atomic force microscopy images of the quantum structures grown on MnAs demonstrated the existence of two types of regions on the surface: protruded islands with micrometric sizes, surrounded by areas of small-scale roughness. Magnetic force microscopy study of these samples revealed a magnetic domain structure only on the above mentioned islands. The (II,Mn)VI quantum wells grown on GaMnAs films exhibited relatively smooth surface, but no magnetic force microscopy signal was measurable either before or after magnetizing the sample. In the luminescence spectra of all our quantum structures the emission attributed to CdMnTe quantum wells was observed. The influence of magnetization on the luminescence line position was investigated.
10
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Magnetic Force Microscopy Study of Zn_{1-x}Co_{x}O Nanowires Grown by Rapid Thermal Evaporation

64%
Aleszkiewicz M., Fronc K., Aleszkiewicz P., Zaleszczyk W., Dziawa P., Wojciechowski T., Wojtowicz T., Karczewski G.
Acta Physica Polonica A
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2009
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vol. 116
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issue 5
865-867
EN
In this work we studied domain structure of Zn_{1-x}Co_{x}O nanowires which are single arms of tetrapode crystals. The as-grown material exhibits hysteretic behavior even at room temperature as revealed by SQUID mesurements. In order to get insight into the magnetic properties of individual tetrapodes they were dismembered into nanowires of nanometric diameters, deposited on a flat substrate and imaged by magnetic force microscopy. A magnetic interaction between the magnetic force microscopy probe and single nanowires has been detected which confirms that nanometric volume of the material possesses a magnetic moment. The magnetic force microscopy contrast is attractively independent of the tip magnetization direction which indicates that shape anisotropy of nanowires is not strong enough to prevent occurrence of tip-induced magnetic field disturbance.
11
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Atomic Force Microscopy Study of a Voltage Effect on CdZnTe Crystal Dimensions

64%
Aleszkiewicz P., Wojciechowski T., Fronc K., Kolkovsky V., Janik E., Jakieła R., Mycielski A., Karczewski G., Aleszkiewicz M.
Acta Physica Polonica A
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2008
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vol. 114
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issue 5
1041-1047
EN
In this work we studied the influence of an external electric voltage on spatial dimensions of CdZnTe mixed crystals. In order to get an absolute magnitude of the sample thickness and to gain insight to the changes of lateral dimension, in quasi-bulk 3 μm thick CdZnTe layers grown by molecular beam epitaxy square craters were formed by ion sputtering in a secondary ion mass spectrometer. The vertical and lateral dimensions of the craters were studied by the atomic force microscopy. The atomic force microscopy measurement revealed that the thickness of the CdZnTe layer increases in a result of applying a single voltage pulse to the sample surface and decreases reversibly after applying reversely biased voltage. The voltage triggering was high enough to switch the conductivity state of the sample i.e., the effect of thickness change is accompanied by the effect of conductivity switching. The thickness change is significant, reaching several percents of the entire layer thickness.
12
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Optimization of the Superconducting Properties of Laser Ablated YBa_2Cu_3O_{7-δ} Films on CeO_2-Buffered Sapphire

64%
Abal'osheva I., Zaytseva I., Aleszkiewicz M., Syryanyy Y., Gierłowski P., Abal'oshev O., Bezusyy V., Cieplak M.
Acta Physica Polonica A
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2012
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vol. 121
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issue 4
805-807
EN
We use pulsed laser deposition to grow YBa_2Cu_3O_{7-δ} (YBCO) superconducting films for microwave applications. The films are grown on R-cut sapphire substrates, with CeO_2 buffer layers, which are re-crystallized at high temperature prior to YBCO growth. Using the atomic force microscopy (AFM) and X-ray diffractometry we determine the optimal temperature for recrystallization (1000°C) and the optimal buffer layer thickness (30 nm). The properties of YBCO films of various thickness, grown on the optimized CeO_2 buffer layers, are studied using several methods, including AFM, magnetooptical imaging, and transport experiments. The YBCO film roughness is found to increase with the increasing film thickness, but the magnetic flux penetration in the superconducting state remains homogeneous. The superconducting parameters (the critical temperature and the critical current density) are somewhat lower than the similar parameters for YBCO films deposited on mono-crystalline substrates.
13
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Photoluminescence Properties of ZnO and ZnCdO Nanowires

52%
Zaleszczyk W., Fronc K., Aleszkiewicz M., Paszkowicz W., Wróbel J., Dłużewski P., Kret S., Klepka M., Kłopotowski Ł., Karczewski G., Wojtowicz T.
Acta Physica Polonica A
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2007
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vol. 112
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issue 2
357-362
EN
We report on the photoluminescence studies of ZnO and ZnCdO nanowires grown on SiO_2/Si substrates by low-pressure vapor phase synthesis. X-ray diffraction and transmission electron microscopy measurements show that the crystallographic structure of these ZnO and ZnCdO nanowires is of wurtzite-type with a high crystal perfection. Surface morphology of samples was determined by scanning electron microscopy and atomic force microscopy. The photoluminescence spectra of as-grown nanowires, nanowires extracted from the substrate and deposited onto Si wafer, and nanowires dispersed in ethanol by sonication were investigated at room temperature and compared to each other. The temperature dependence of the near band-gap photoluminescence emitted by the as-grown nanowires was also measured and analyzed.
14
Content available remote

Growth and Properties of ZnMnTe Nanowires

46%
Zaleszczyk W., Janik E., Presz A., Szuszkiewicz W., Morhange J., Dłużewski P., Kret S., Kirmse H., Neumann W., Dynowska E., Domagała J., Caliebe W., Aleszkiewicz M., Pacuski W., Golnik A., Kossacki P., Baczewski L., Petroutchik A., Karczewski G., Wojtowicz T.
Acta Physica Polonica A
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2007
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vol. 112
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issue 2
351-356
EN
Catalytically enhanced growth of ZnMnTe diluted magnetic semiconductor nanowires by molecular beam epitaxy is reported. The growth is based on the vapor-liquid-solid mechanism and was performed on (001) and (011)-oriented GaAs substrates from elemental sources. X-ray diffractometry, scanning and transmission electron microscopy, atomic force microscopy, photoluminescence spectroscopy, and Raman scattering were performed to determine the structure of nanowires, their chemical composition, and morphology. These studies revealed that the obtained ZnMnTe nanowires possess zinc-blende structure, have an average diameter of about 30 nm, typical length between 1 and 2μm and that Mn^{2+} ions were incorporated into substitutional sites of the ZnTe crystal lattice.
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