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Wyszukujesz frazę "Łusakowski, A." wg kryterium: Autor


Tytuł:
Transport and Magnetic Study of Gd Ions in Pb$\text{}_{1-y}$Sn$\text{}_{y}$Te
Autorzy:
Story, T.
Arciszewska, M.
Łazarczyk, P.
Łusakowski, A.
Górska, M.
Dobrowolski, W.
Witkowska, B.
Grodzicka, E.
Gałązka, R. R.
Powiązania:
https://bibliotekanauki.pl/articles/1968424.pdf
Data publikacji:
1997-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Ck
75.30.Et
Opis:
Electric conductivity, Hall effect and magnetic susceptibility of Pb$\text{}_{1-x-y}$ Sn$\text{}_{y}$Gd$\text{}_{x}$Te mixed crystals with 0.13 ≤ y ≤ 0.93 and 0.001 ≤ x ≤ 0.04 were experimentally studied over the temperature range 4K ≤ T ≤ 300 K. The incorporation of Gd ions into the Pb$\text{}_{1-y}$Sn$\text{}_{y}$Te matrix results in semi-metallic n-type conductivity of the crystals with y < 0.6. For crystals with y > 0.6 one observes only semi-metallic p-type conductivity. We present a model explaining these results in terms of the Sn composition dependence of the location of Gd$\text{}^{2+}\text{}^{/}\text{}^{3+}$ level with respect to the band edges of PbSnGdTe.
Źródło:
Acta Physica Polonica A; 1997, 92, 5; 997-1000
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
THz Time Domain Spectroscopy of Thin Gold Layers on GaAs
Autorzy:
Szczytko, J.
Adomavicius, R.
Papis, E.
Barańska, A.
Wawro, A.
Krotkus, A.
Piętka, B.
Łusakowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1417930.pdf
Data publikacji:
2012-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.66.Bz
78.68.+m
Opis:
Thin layers of Au with the thickness of several nanometers were prepared on a semi-insulating GaAs substrate. The layers' thickness was determined by ellipsometry. THz time-domain spectroscopy was applied to determine a complex index of refraction of thin Au layers. The obtained results allow for a more precise modeling of the performance of semiconductor devices at THz frequencies.
Źródło:
Acta Physica Polonica A; 2012, 122, 6; 1118-1120
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Terahertz Detection by the Entire Channel of High Electron Mobility Transistors
Autorzy:
Sakowicz, M.
Łusakowski, J.
Karpierz, K.
Knap, W.
Grynberg, M.
Köhler, K.
Valusis, G.
Gołaszewska, K.
Kamińska, E.
Piotrowska, A.
Caban, P.
Strupiński, W.
Powiązania:
https://bibliotekanauki.pl/articles/1811985.pdf
Data publikacji:
2008-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.75.+a
78.20.Ls
85.30.Tv
07.57.Kp
Opis:
GaAs/AlGaAs and GaN/AlGaN high electron mobility transistors were used as detectors of THz electromagnetic radiation at liquid helium temperatures. Application of high magnetic fields led to the Shubnikov-de Haas oscillations of the detection signal. Measurements carried out with a simultaneous modulation of the intensity of the incident THz beam and the transistor gate voltage showed that the detection signal is determined by the electron plasma both in the gated and ungated parts of the transistor channel. This result is of importance for understanding the physical mechanism of the detection in high electron mobility transistors and for development of a proper theoretical description of this process.
Źródło:
Acta Physica Polonica A; 2008, 114, 5; 1343-1348
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Raman Spectroscopy of Co-Doped ZnO Bulk Crystals
Autorzy:
Szuszkiewicz, W.
Morhange, J. F.
Gołacki, Z.
Łusakowski, A.
Schumm, M.
Geurts, J.
Powiązania:
https://bibliotekanauki.pl/articles/2047700.pdf
Data publikacji:
2007-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
78.30.Fs
Opis:
Low-temperature Raman spectra of a bulk mixed crystal Zn$\text{}_{1-x}$Co$\text{}_{x}$O (x = 0.016) are shown and analyzed. Besides the common modes of the ZnO host lattice, electronic transitions related to the presence of Co$\text{}^{2+}$ ions at the Zn sites are observed. In spite of the low Co concentration the presence of collective excitations corresponding to Co and CoO precipitates is also revealed.
Źródło:
Acta Physica Polonica A; 2007, 112, 2; 363-368
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Possible Long Time Tails in Current-Current Correlation Function for Two-Dimensional Electron Gas in Random Magnetic Field
Autorzy:
Łusakowski, A.
Turski, Ł. A.
Powiązania:
https://bibliotekanauki.pl/articles/1968462.pdf
Data publikacji:
1997-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.60.+w
72.10.-d
Opis:
We consider a two-dimensional degenerate electron gas in the presence of perpendicular random magnetic field. The magnetic field disorder which is assumed to be Gaussian is characterized by two parameters. The first is proportional to the amplitude of local magnetic field fluctuations. The second one characterizes the disorder on the longer scale - we call it the screening length. Using the Kubo formula for the conductivity we have found a class of diagrams which leads to the long time tails in the current-current correlation function. For short times in comparison with the diffusion time corresponding to the screening length this function behaves like logarithm of time, for longer times it decays like t$\text{}^{-1}$ which of course brings into question the diffusive character of the behavior of the charged particle in random magnetic field widely assumed in the literature.
Źródło:
Acta Physica Polonica A; 1997, 92, 6; 1109-1115
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Possible Origin of Large Value of Magnetic Anisotropy Constant in PbSnMnTe Mixed Crystals
Autorzy:
Łusakowski, A.
Story, T.
Gałązka, R. R.
Powiązania:
https://bibliotekanauki.pl/articles/1929772.pdf
Data publikacji:
1993-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Gw
Opis:
In PbSnMnTe crystals with the concentration of conducting holes of the order of 10$\text{}^{21}$ cm$\text{}^{-3}$, the magnetic anisotropy constant K measured in ferromagnetic resonance experiments is nearly one order of magnitude larger than expected. In the present paper we investigate a contribution ΔK to the anisotropy constant, origin of which is the s-d interaction and the spin-orbit coupling.
Źródło:
Acta Physica Polonica A; 1993, 84, 4; 829-831
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Possible Analogy between Spin-Glasses and Systems
Autorzy:
Łusakowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1920977.pdf
Data publikacji:
1992-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Nr
71.55.Dp
Opis:
An analogy between a spin-glass and a material containing DX centers is postulated. The basis of the analogy is the formal identity of the Hamiltonians of these two systems. A correspondence between parameters of the spin-glass and of the DX system is established. Experiments which could support the above idea are proposed.
Źródło:
Acta Physica Polonica A; 1992, 82, 4; 620-622
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Non-Ohmic Conductivity of High Resistivity CdTe
Autorzy:
Łusakowski, J.
Szczytkowski, J.
Szadkowski, K.
Kamińska, E.
Piotrowska, A.
Karczewski, G.
Wojtowicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/1933850.pdf
Data publikacji:
1995-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.-r
Opis:
Conductivity measurements were carried out at room temperature on samples of nominally undoped Bridgman, bulk crystals and MBE-grown layers of CdTe. The samples were equipped with indium contacts which made it possible to determine the voltage distribution along the path of the current flow. The results show that for both types of CdTe almost all of the applied voltage drops in the vicinity of the positively biased contact. The resistance of the samples was shown not to depend on the distance between the pads. The results agree with predictions of model of current injection into semiconductors with deep traps.
Źródło:
Acta Physica Polonica A; 1995, 88, 4; 803-806
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetoconductivity of GaAs Transistors as Detectors of THz Radiation
Autorzy:
Łusakowski, J.
Knap, W.
Kamińska, E.
Piotrowska, A.
Gavrilenko, V.
Powiązania:
https://bibliotekanauki.pl/articles/2035755.pdf
Data publikacji:
2003-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.30.+q
73.61.Ey
Opis:
Magnetotransport characterisation of field effect transistors processed on GaAs/GaAlAs heterostructure was done at 4.2 K for magnetic fields (B) up to 7 T. Three field effect transistors were processed on a single dice and differed by the length (L) of the gate. Electron mobility (μ) in field effect transistors was estimated from dependence of transistor's conductivity vs. B. The results show a decrease inμ with decreasing L that suggests that scattering by edges of the gated part of a transistor limits the electron mobility. Quality factor (Q) of transistors as resonant detectors of THz radiation was calculated. A high value of Q shows that such field effect transistors with sub-micron L are promising devices that can operate at THz frequencies.
Źródło:
Acta Physica Polonica A; 2003, 103, 6; 545-551
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Specific Heat of Pb$\text{}_{1-x}$Eu$\text{}_{x}$Te
Autorzy:
Górska, M.
Łusakowski, A.
Jędrzejczak, A.
Gołacki, Z.
Anderson, J. R.
Balci, H.
Powiązania:
https://bibliotekanauki.pl/articles/2038143.pdf
Data publikacji:
2004-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.70.-d
75.40.Cx
Opis:
The temperature dependence of the magnetic specific heat was studied experimentally and theoretically in the semimagnetic semiconductor Pb$\text{}_{1-x}$Eu$\text{}_{x}$Te for x=0.027 and x=0.073, over the temperature range from 0.5 K to 15 K, in magnetic fields up to 2 T. In zero magnetic field at about 2 K there was a broad maximum in the magnetic specific heat, which was much higher than that predicted by the model of superexchange interaction between nearest neighbors; the maximum values increased with magnetic field. The experimental data were analyzed in the framework of a model which takes into account the spin splitting of the ground state of a single Eu2+ ion in the presence of local lattice distortions in the Pb$\text{}_{1-x}$Eu$\text{}_{x}$Te mixed crystal. The model describes well the experimental data, especially for lower x-values, where the contribution from singlets dominates.
Źródło:
Acta Physica Polonica A; 2004, 105, 6; 631-636
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of Sn$\text{}_{1-x}$Gd$\text{}_{x}$Te (0.002 ≤ x ≤ 0.09)
Autorzy:
Story, T.
Arciszewska, M.
Dobrowolski, W.
Gołacki, Z.
Górska, M.
Grodzicka, E.
Łusakowski, A.
Dynowska, E.
Witkowska, B.
Powiązania:
https://bibliotekanauki.pl/articles/1952098.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Ck
75.30.Et
Opis:
Magnetic, transport and structural properties of bulk crystals of Sn$\text{}_{1-x}$Gd$\text{}_{x}$Te with Gd content 0.002 < x < 0.09 and varying carrier concentrations obtained by an isothermal annealing were studied in the temperature range T = 1.5 - 80 K. We found the effect of resonant increase in antiferromagnetic spin-spin exchange interactions in the crystals with 0.025 ≤ x ≤ 0.05. No effect was found in crystals either with higher (x > 0.05) or with lower (x < 0.025) Gd concentration. The observed Gd composition dependence of the magnetic and transport properties of SnGdTe can be explained in a proposed model relating these experimental properties to the Gd composition induced shift of the position of Gd$\text{}^{3+}\text{}^{/}\text{}^{2+}$ level with respect to the top of the valence band of SnGdTe.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 935-938
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Anisotropy in (Ge,Mn)Te Layers
Autorzy:
Knoff, W.
Łusakowski, A.
Wołoś, A.
Story, T.
Powiązania:
https://bibliotekanauki.pl/articles/1386196.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
75.30.Gw
76.50.+g
Opis:
Ferromagnetic resonance study of magnetic anisotropy is presented for thin layers of IV-VI diluted magnetic semiconductor (Ge,Mn)Te with Mn content of 12 and 21 at.% grown by molecular beam epitaxy on BaF₂ (111) substrates. The layers with low Mn content grow in the rhombohedral crystal structure and exhibit perpendicular magnetic anisotropy whereas the layers with Mn content higher than about 20 at.% are of cubic (rock-salt) structure and show regular easy-plane type magnetic anisotropy. The quantitative analysis of the angular dependence of the ferromagnetic resonant field is performed taking into account the magnetic energy contributions due to rhombohedral distortion (axial term along the (111) growth direction of the layer) and the crystal field terms allowed for ferromagnetic systems of rhombohedral symmetry.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 404-406
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Anisotropy in GeMnTe - ab initio Calculations
Autorzy:
Łusakowski, A.
Bogusławski, P.
Powiązania:
https://bibliotekanauki.pl/articles/1376168.pdf
Data publikacji:
2014-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Gw
71.15.Mb
Opis:
Density functional theory calculations of the energy of magnetic anisotropy in GeMnTe were performed using OpenMX package with fully relativistic pseudopotentials. The discussion of microscopic origin of magnetic anisotropy was conducted. The main conclusion is that the magnetic anisotropy is caused by interplaty between spin-orbit and Coulomb interactions. The discussion includes also the influence of the free carriers concentration on the amplitude of energy of magnetic anisotropy. The important role of the chemical disorder is also pointed out.
Źródło:
Acta Physica Polonica A; 2014, 126, 5; 1177-1179
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low-Frequency Raman Spectrum οf Bulk $Zn_{0.984}Co_{0.016}O$ Crystal
Autorzy:
Szuszkiewicz, W.
Łusakowski, A.
Morhange, J.
Gołacki, Z.
Arciszewska, M.
Brodowska, B.
Kanehisa, M.
Klepka, M.
Dobrowolski, W.
Powiązania:
https://bibliotekanauki.pl/articles/1807848.pdf
Data publikacji:
2009-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
78.30.Fs
Opis:
The influence of possible presence of $Co^{2+}$ ion pairs in a bulk $Zn_{1-x}Co_{x}O$ mixed crystal on the low-frequency part of the Raman spectrum is discussed. Two effects can be taken into account in the theoretical considerations when analyzing the energy level scheme corresponding to Co ions. The first is a local lattice deformation in the vicinity of $Co^{2+}$ ion due to a presence of the second ion, smaller than the host ZnO lattice cation. Such deformation creates a trigonal field, which can only slightly modify the energy levels of $Co^{2+}$ ion. The second effect, which results from an antiferromagnetic superexchange interaction between two $Co^{2+}$ ions is responsible for a new set of energy levels. The Raman data taken at low temperature on the sample corresponding to the composition x = 0.016 demonstrated the presence of two structures at about 6 $cm^{-1}$ and 13 $cm^{-1}$. These structures may be interpreted as electronic transitions between the ground state and the first excited state of a single $Co^{2+}$ ion in the substitution site of ZnO lattice and as a similar transition for $Co^{2+}$ ion pair, respectively.
Źródło:
Acta Physica Polonica A; 2009, 116, 1; 103-106
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Is the Magnetism of HgSe:Fe Clearly Understood?
Autorzy:
Dybko, K.
Łusakowski, A.
Kossut, J.
Arciszewska, M.
vd Linden, P. J. E. M.
Wittlin, A.
Perenboom, J. A. A. J.
Mycielski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1931952.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Hx
75.20.Hr
Opis:
The high magnetic field magnetization measurements of low composition Hg$\text{}_{1-x}$Fe$\text{}_{x}$Se (0.0002 < x < 0.003) at temperatures ranging from 1.6 K to 40 K and in magnetic fields up to 20 T are reported. The magnetization in a sample containing only Fe$\text{}^{3+}$ ions (x = 0.0002) is described by the Brillouin function (j = 5/2). The magnetization in the sample codoped with Ga, containing only Fe$\text{}^{2+}$ is well described in the model of isolated Fe$\text{}^{2+}$ ions. The latter model takes into account the tetrahedral crystal field, the spin-orbit interaction and the Zeeman term. On the other hand, the magnetization of sample with both Fe$\text{}^{3+}$ and Fe$\text{}^{2+}$ present simultaneously (x = 0.003) is shown to be different from a simple additive superposition of the contributions due to Fe$\text{}^{3+}$ and Fe$\text{}^{2+}$ subsystems. The possible origin of this discrepancy is discussed.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 193-196
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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