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1
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Manipulations with Atoms and Clusters

100%
Czajka R.
Acta Physica Polonica A
|
1995
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vol. 88
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issue 5
813-828
EN
The investigation and fabrication of nanometer-scale structures becomes a reality due to the development of scanning tunneling microscopy and related techniques. The final goal, manipulations with the individual atoms and molecules, has been achieved. D.M. Eigler used the scanning tunneling microscope (working at low temperatures ca. 4 K) to position individual xenon atoms on a single-crystal nickel surface with atomic precision. Mesoscopic systems composed of metallic or non-metallic clusters are intensively studied because of their new and interesting properties, and perspectives of subsequent application in nanolithography in order to create various structures of a very high degree of miniaturization. In this review, (i) the potential of scanning probe microscopes for revealing subtle details of surfaces down to atomic resolution is presented, (ii) a variety of different atomic manipulations processes and other surface modifications are reviewed against the background of different, more or less universal approaches, and finally (iii) a few examples of cluster surface structures created and/or modified by means of scanning tunneling microscope are demonstrated.
2
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Superparamagnetic Grains as Source of Giant Magnetoresistance Effect in Discontinuous Co/Ag Multilayers

51%
Luciński T., Stobiecki F., Dubowik J., Czajka R.
Acta Physica Polonica A
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1997
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vol. 91
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issue 2
269-272
EN
The as-deposited and annealed Co/Ag discontinuous multilayer-like structures were examined. Discontinuous Co sublayers are thought to consist of fine superparamagnetic and ferromagnetic grains. Using the bimodal superparamagnetic grain sizes distribution the GMR(H) dependencies were successfully modelled with the use of two Langevin functions simulating the magnetization of the superparamagnetic grains.
3
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MFM Investigations of [NiFe/Au/Co/Au]_N Multilayers

51%
Bazarnik M., Dabrowski J., Czajka R.
Acta Physica Polonica A
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2009
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vol. 115
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issue 1
220-222
EN
Magnetic force microscopy measurements combined with computer simulations were applied to investigate the strengths of magnetic field over the [NiFe/Au/Co/Au]_N multilayers with in-plane and out-of-plane anisotropy observed for NiFe and Co layers, respectively. All measurements were performed in air atmosphere at room temperature. Dimensions and density of magnetic domains were estimated. The distribution of magnetization directions was deduced from comparison of magnetic force microscopy with the simulation results. Some sort of modulation in stray magnetic field was observed, but till now it is of unknown origin.
4
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STM/STS Investigations of Surface Evolution of Si(111)-(7×7) Induced with Nickel

51%
Gutek J., Szuba S., Czajka R.
Acta Physica Polonica A
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2003
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vol. 104
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issue 3-4
345-350
EN
By means of scanning tunneling microscopy and spectroscopy we studied the surface evolution of Si(111)-(7×7) induced with nickel followed by annealing at specified temperatures (400, 600, and 800˚C). Nickel evaporation resulted with 0.05 ML and 0.2 ML coverage was carried out at room temperature with the use of solid phase epitaxy. The characteristic phase formations occurred after gradual annealing the sample depending on the amount of deposited material. At very low coverages scanning tunneling microscopy observation showed two types of ring clusters (1×1 -RC and clusters of the √(19)×√(19) reconstruction) accompanied by the Si(111)-(7×7) surface reconstruction. All above-mentioned phases appeared in that order as the annealing temperature increased. Deposition of about 0.2 ML of Ni followed by annealing at 600˚C formed extended regions of 1×1 nickel silicide reconstruction. Very clear, extended regions of √(19)×√(19) reconstruction appeared when annealed to 800˚C. The electronic properties of observed structures have been studied by the scanning tunneling spectroscopy. Spectroscopy curves measured above certain surface formations revealed the presence of the Si rest atom, NiSi, and NiSi_2 local density of electronic states.
5
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STM/STS Studies of Self-Organized Growth of Iron Silicide Nanocrystals on Vicinal Si(111) Surface

51%
Wawro A., Suto S., Czajka R., Kasuya A.
Acta Physica Polonica A
|
2003
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vol. 104
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issue 3-4
303-319
EN
The evolution of iron silicide structure grown by solid state epitaxy on Si(111) vicinal surface was investigated by scanning tunnelling microscopy. The reactions, which occur on the surface, are compared for two various Fe coverages: 0.33 and 2 monolayers. The annealing at 250˚C does not enable substantial recovery of the surface ordering, deteriorated by Fe deposition at room temperature. The onset of 2×2 surface reconstruction is observed upon annealing at 400˚C. A three-dimensional growth tendency of iron silicide crystallites on a bare Si(111) 7×7 surface was found at 700˚C. In the case of 2 monolayer coverage crystallites nucleate along the edges of substrate terraces forming a regular array of nanometer size dots. Basing on atomically resolved spectroscopic effects and statistical considerations, structure of iron silicide nanocrystallites as well as Schottky-like character of the barrier at the interface between metallic crystallite and semiconducting substrate is deduced.
6
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STM/AFM Images and Tunneling Spectra of Nd_{2-x}Ce_{x}CuO_{4-y} Single Crystals

51%
Susła B., Sadowski W., Klimczuk T., Czajka R.
Acta Physica Polonica A
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1997
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vol. 92
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issue 1
209-214
EN
The results of the scanning tunneling microscopy and spectroscopy as well as atomic force microscopy measurements on the Nd_{2-x}Ce_{x}CuO_{4-y} single crystals in ambient conditions are reported. Using the scanning tunneling microscopy we were able to modify the Nd_{2-x}Ce_{x}CuO_{4-y} ab-plane in air under the conditions of sample bias voltage V_{t}=500 mV and set current I_{s}=0.3 nA. It is possible to prepare atomically flat and clean surfaces as well as to create new structures in a nanometer scale in these electron-doped materials. The similar processes were not observed during atomic force microscopy imaging.
7
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SPM Characterization of Titanium Disilicide Nanostructures Grown on a Ni-Modified Si(100) Substrate

51%
Koczorowski W., Bazarnik M., Czajka R.
Acta Physica Polonica A
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2011
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vol. 120
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issue 3
480-484
EN
The paper presents our recent investigations of the early stage growth of titanium silicides on a modified Si(100) substrate. The substrate was modified by deposition of a minute amount of Ni atoms, and the subsequent flash annealing. This process led to the creation of parallel defect lines on the Si(100) surface. We expected TiSi_2 to form elongated structures on top and/or between the defect lines. Though this idea failed, stable nanostructures were observed and characterized using scanning probe microscopy (scanning tunneling microscopy and atomic force microscopy) methods.
8
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Surface of BiSrCaCuO Single Crystal Observed by Means of Scanning Tunneling Microscope

45%
Witek A., Reich A., Czajka R., Pajączkowska A., Rauluszkiewicz J.
Acta Physica Polonica A
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1991
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vol. 80
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issue 5
717-722
EN
The topographic images of a Bi_{0.7}Pb_{0.3}SrCaCu_{1.8}O_{x} single crystal were studied by means of the scanning tunneling microscope. The structure of terraces and steps seen on the surface reflects the crystallographic structure of bulk.
9
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STM and STS Investigations of Bi_2Te_3 Surface

39%
Winiarz S., Czajka R., Suto S., Lośtak P., Szuba S., Kasuya A.
Acta Physica Polonica A
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2003
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vol. 104
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issue 3-4
389-395
EN
We carried out scanning tunneling microscopy/spectroscopy studies of Bi_2Te_3 surface, which, to the best of our knowledge, had not been attempted so far. We got images of surface of the material in many scales from micrometers to nanometers, which showed a layered structure of Bi_2Te_3, with many monoatomic terraces. We found agreement between measured heights and corresponding bulk crystal structure derived from X-ray data. In nanoscale we obtained an atomic resolution. Using scanning tunneling spectroscopy we carried out examination of the electronic structure. We observed different I-V characteristics and contrast on current imaging tunneling spectroscopy maps on non equivalent terraces. The dI/dV (~ density of states) curves referred to those terraces were compared with theoretically calculated by Larson et al. density of states derived from Bi p and Te-1 p orbitals. The analysis of our results allowed us to distinguish bismuth from tellurium planes.
10
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Point-Contact I-V Characteristics of the Electroluminescent ZnS:Mn,Cu Thin Films Studied by STM

39%
Szuba S., Czajka R., Gordon W., Polewska W., Raułuszkiewicz J., Reich A.
Acta Physica Polonica A
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1991
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vol. 79
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issue 2-3
171-174
EN
STM images of ZnS:Mn,Cu thin films and spatially resolved current-voltage characteristics are shown. The results make possible to estimate the morphology and conductivity distribution with nanometer resolution.
11
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STM/AFM Observations of Co/Cu Magnetic Multilayers

39%
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.
12
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Content available

Variable Temperature STM/STS Investigations of Ag Nanoparticles Growth on Semiconductor Surfaces

33%
Suto S., Czajka R., Szuba S., Shiwa A., Winiarz S., Nagashima H., Kato H., Yamada T., Kasuya A.
Acta Physica Polonica A
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2003
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vol. 104
|
issue 3-4
289-302
EN
We have investigated the growth of Ag nanoparticles deposited on Si(111), H/Si(111)-(1×1) and Bi_2Te_3 substrates using a variable temperature scanning tunneling microscopy. These substrates are different as regards the model system for cluster and islands growth at the nanometer scale. Ag was evaporated onto the sample mounted at the scanning tunneling microscopy stage in vacuum of 10^{-10} Torr range during evaporation. The substrates were kept at different temperatures: -150˚C, room temperature, and 300˚C during the deposition process. In general, we have observed 3D growth mode up to several ML coverage. The density of clusters and their size were functions of the substrate's temperature during the deposition process - a higher density and a smaller size at -150˚C were in opposition to the 300˚C results - a lower density and a larger size. Low temperature depositions led to continuous layers above 10 ML coverage but the surface was covered by small Ag clusters of 1-2 nm in heights and 2-3 nm in diameters. The log-log graphs of height and projected diameter of Ag clusters revealed different slopes indicating different growth mechanisms at low and high temperatures. We obtained the value of n=0.25±0.02, typical of the so-called droplet model of cluster growth, only at 300˚C. Scanning tunneling spectroscopy measurements revealed clearly different I-V (and dI/dV vs. bias voltage) curves measured above clusters and directly above the substrate. In discussion, we compared our results to theoretically calculated density of states from other papers, finding conformity for partial density of states.
13
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Chemical Reactions and Electronic Functions of Carbon Cluster Arrays Studied by Scanning Tunneling Spectroscopy and High-resolution Electron Energy Loss Spectroscopy

33%
Kasuya A., Hu C., Suto S., Tohji K., Takahashi H., Czajka R., Wawro A., Nishina Y.
Acta Physica Polonica A
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1998
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vol. 93
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issue 2
317-322
EN
Novel nanometer scale structures have been produced by thermal heating or laser irradiation on the surface of single- and multi-layers of C_{60} and C_{84} on Si. These structures were examined by combined measurements of scanning tunneling spectroscopy and high resolution electron energy loss spectroscopy. The results show specific chemical reactions of substrate with carbon clusters having single- and double-bonded network. Covalent bonds are formed in some of these chemical reactions.
14
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Exchange Coupling Effects in Naturally Oxidised Ultrathin Iron Film

33%
Dawczak-Dębicki H., Marczyńska A., Rogowska A., Wachowiak M., Nowicki M., Pacanowski S., Jabłoński B., Czajka R., Smardz L.
Acta Physica Polonica A
|
2018
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vol. 133
|
issue 3
601-604
EN
Oxidation process of Fe films under atmospheric conditions is depth limited such that an oxide covering layer with a well-defined thickness is formed by which the underlying metal is prevented from further oxidation. Iron thin film with an initial thickness d_{i}=4 nm was deposited onto 1.6 nm - V(110) buffer layer using UHV magnetron sputtering. The planar growth of Fe oxides was revealed by atomic force microscopy. X-ray photoelectron spectroscopy studies performed after 250 days of oxidation revealed formation of a hematite (α-Fe₂O₃) ultrathin film on the metallic rest of iron. Furthermore, low temperature magnetic measurements of the oxidised Fe ultrathin film revealed an exchange anisotropy which is imposed to the metallic rest. As a result, we have observed at low temperatures a shift and broadening of the hysteresis loops due to the exchange interaction at the metal-oxide interface.
15
Content available remote

Natural Oxidation of thin Fe Films on V Buffer Layer

27%
Dawczak-Dębicki H., Marczyńska A., Rogowska A., Wachowiak M., Nowicki M., Pacanowski S., Jabłoński B., Kowalski W., Grembowski J., Czajka R., Smardz L.
Acta Physica Polonica A
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2017
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vol. 132
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issue 4
1272-1276
EN
We have studied oxidation kinetics of Fe thin film under atmospheric conditions using the fact that metallic iron is a ferromagnet but ultrathin natural iron oxides are approximately nonmagnetic at room temperature. As a consequence, oxidation is associated with a loss in total Fe magnetic moment. Results show that the sample with an initial Fe thickness equal to 10 nm oxidize relatively fast (time constant τ=0.05 day), whereby a constant amount of 2.5 nm of metal is transformed into oxides. For lower iron initial thickness (d_{i}=4 nm) the time constant for oxidation significantly increases reaching a value of 2 days. Furthermore, X-ray photoelectron spectroscopy studies performed after 144 days of oxidation revealed formation of hematite (α-Fe₂O₃) thin film on the metallic rest of iron.
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