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    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:
    Erratum. Possible Long Time Tails in Current-Current Correlation Function for Two-Dimensional Electron Gas in Random Magnetic Field (Acta Phys. Pol. A 92, 1109 (1997))
    Autorzy:
    Łusakowski, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1968868.pdf
    Data publikacji:
    1998-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Źródło:
    Acta Physica Polonica A; 1998, 93, 3; 563
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Free Carrier Concentration Dependence of Gd-Gd Exchange Constant in SnTe:Gd
    Autorzy:
    Łusakowski, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1934066.pdf
    Data publikacji:
    1995-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.30.Hx
    75.30.Et
    71.70.Gm
    Opis:
    In some samples of SnTe:Gd the measured paramagnetic Curie temperature strongly depends on the Fermi level position. The semi-quantitative theory which explains this effect is presented. The theory is based on Kasuya's model of exchange interaction between two 4f spins of rare earth ions. In this model the interaction between 4f electrons and the valence band goes via Gd atomic 5d orbitals which, contrary to the 4f orbitals are much more extended in space. The exchange integral and the paramagnetic Curie temperature dependence on the Fermi level position are calculated.
    Źródło:
    Acta Physica Polonica A; 1995, 88, 5; 1018-1022
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Distance Dependence of the Mn-Mn Exchange Interaction in IV-VI Semimagnetic Semiconductors
    Autorzy:
    Łusakowski, A.
    Górska, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/2036858.pdf
    Data publikacji:
    2003-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.70.Gm
    75.30.Hx
    Opis:
    In the present paper we calculate the exchange interaction between two manganese ions in IV-VI semiconductors with the rocksalt structure. The method of calculations is based on the fourth order perturbation theory with respect to hybridization between band states and localized d orbitals of Mn ions. This hybridization is described by three Harrison integrals: V$\text{}_{pdσ}$,V$\text{}_{pdπ}$, and V$\text{}_{sdσ}$. The band states of IV-VI semiconductor are obtained from the semiempirical tight binding model built from s and p orbitals of cations and anions. The resulting exchange term in the Hamiltonian is of the form -Σ$\text{}_{i,j=xyz}$J$\text{}_{ ij}$Ŝ$\text{}_{i}^{1}$Ŝ$\text{}_{j}^{2}$, however nondiagonal terms of the exchange integral tensor J$\text{}_{i≠j}$ are very small. The dependence of J$\text{}_{ij}$ on the Mn-Mn distance is non-monotonic. We also discuss the influence of the local crystal deformations on the exchange integral.
    Źródło:
    Acta Physica Polonica A; 2003, 103, 6; 659-664
    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:
    Analysis of Chemical Disorder in $Pb_{1-x}Ge_{x}Te$
    Autorzy:
    Radzyński, T.
    Łusakowski, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1811977.pdf
    Data publikacji:
    2008-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    31.15.A-
    61.43.-j
    61.43.Bn
    Opis:
    The PbGeTe crystal lattice is locally deformed due to different ionic radii of cations and their random placement in the lattice. It is important to quantitatively characterize such microscopic disorder because local deformations have significant influence on the properties of magnetic ions introduced to such crystal. The simples method to study microscopic disorder is to consider purely classical model of the lattice in which neighboring atoms are connected by springs with properly chosen spring constant and equilibrium lengths. In the present work, using ab initio methods we discuss applicability of the springs-atoms model to the real crystal. We also explain results of extended X-ray absorption fine structure experiments performed on PbGeTe mixed crystals.
    Źródło:
    Acta Physica Polonica A; 2008, 114, 5; 1317-1322
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of Spin-Orbit Interaction on Band Structure and Elastic Properties of PbTe
    Autorzy:
    Radzyński, T.
    Łusakowski, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1791363.pdf
    Data publikacji:
    2009-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    31.15.A-
    31.15.aj
    71.20.-b
    87.19.rd
    Opis:
    Inclusion of spin-orbit interaction in density functional theory calculations of PbTe band structure leads to wrong results concerning the symmetry of valence and conduction band wave functions. Using two ab initio codes: OpenMX and Quantum Espresso we show that changing the spin-orbit coupling strength in pseudopotentials for Pb it is possible to obtain proper energy gap and wave functions of proper symmetries.
    Źródło:
    Acta Physica Polonica A; 2009, 116, 5; 954-955
    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:
    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:
    Correlation between Magnetic and Electronic Properties of Sn$\text{}_{1-x}$Gd$\text{}_{x}$Te
    Autorzy:
    Łusakowski, A.
    Górska, M.
    Arciszewska, A.
    Grodzicka, E.
    Gołacki, Z.
    Story, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/1931955.pdf
    Data publikacji:
    1995-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.20.Ck
    75.30.Et
    Opis:
    Magnetic susceptibility, electron paramagnetic resonance and transport properties of Sn$\text{}_{1-x}$Gd$\text{}_{x}$Te with 0.04 < x < 0.07 and hole concentrations in the range from 0.7 × 10$\text{}^{20}$ to 16 × 10$\text{}^{20}$ cm$\text{}^{-3}$ were investigated. After annealing of the Sn$\text{}_{1-x}$Gd$\text{}_{x}$Te samples with x < 0.05 in Sn vapor their hole concentration decreased from 5 × 10$\text{}^{20}$ cm$\text{}^{-3}$ to about 3 × 10$\text{}^{20}$ cm$\text{}^{-3}$ and their paramagnetic Curie temperature increased a few times. In samples with x > 0.05 no significant change in the magnetic properties was observed after annealing, even at lower hole concentrations. The results can be explained by assuming that an indirect exchange interaction, 4f-5d-band electrons, is responsible for the coupling among Gd ions.
    Źródło:
    Acta Physica Polonica A; 1995, 87, 1; 197-200
    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:
    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:
    High Field Magnetization of Sn$\text{}_{1-x}$Gd$\text{}_{x}$Te
    Autorzy:
    Górska, M.
    Anderson, J. R.
    Wolters, C.
    Łusakowski, A.
    Story, T.
    Gołacki, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/1969093.pdf
    Data publikacji:
    1998-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.20.Ck
    75.30.Et
    Opis:
    The magnetization of p-type Sn$\text{}_{1-x}$Gd$\text{}_{x}$Te with x up to 0.045 and the hole concentration, p, varying from 2.7 to 8.3×10$\text{}^{20}$ cm$\text{}^{-3}$ has been measured in magnetic fields up to 27 T, at the temperatures 4.2 and 1.3 K. The data were fitted to a magnetization equation with single-ion and pair terms. From comparison of the exchange parameters determined from the high-field magnetization with those previously obtained from the high-temperature magnetic susceptibility it was found that in samples with p>5×10$\text{}^{20}$ cm$\text{}^{-3}$ the exchange was of a short-range type, while in samples with a lower carrier concentration the long-range exchange mechanism was observed.
    Źródło:
    Acta Physica Polonica A; 1998, 94, 2; 347-350
    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:
    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:
    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:
    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
    Tytuł:
    Influence of Impact Ionization of Shallow Donors on Luminescence in GaAs
    Autorzy:
    Wysmołek, A.
    Łusakowski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1932094.pdf
    Data publikacji:
    1995-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    78.55.-m
    72.20.Ht
    Opis:
    Luminescence spectra of n-type molecular beam epitaxial layer and semi-insulating liquid encapsulated Czochralski grown bulk GaAs were measured at liquid helium temperature for zero electric field and for fields which caused impact ionization of shallow donors. Application of the electric field caused a decrease in the luminescence intensity and a broadening of all observed structures. It was found that the electric field changed the luminescence spectrum of the n-type material in a different way than it did in the case of the semi-insulating one. For the n-type sample, an intensity of excitonic lines decreased much more than that of donor-acceptor lines when the electric field grew. A contrary was observed for the semi-insulating sample. An explanation of the result is proposed which takes into account an influence of ionised impurity scattering and localization in fluctuations of the electrostatic potential on the luminescence process.
    Źródło:
    Acta Physica Polonica A; 1995, 87, 1; 261-264
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fractal Dimensions from Chaotic Oscillations in Semi-Insulating GaAs
    Autorzy:
    Zduniak, A.
    Łusakowski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1929673.pdf
    Data publikacji:
    1993-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    05.45.+b
    72.20.Ht
    Opis:
    Relaxation and domain current oscillations in undoped semi-insulating GaAs were observed at room temperature for a broad range of voltage applied to a sample. The oscillations were characterized by a reconstruction of an attractor of the system. An analysis of the attractor helped to discriminate between the two likes of oscillations. A transition from one like of oscillations to the other was connected with a chaotization of the current. A chaotic state of the system was analyzed by calculations of fractal dimensions D$\text{}_{q}$ for -0.6 < g < 40 and the f(α) function.
    Źródło:
    Acta Physica Polonica A; 1993, 84, 3; 575-578
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Autocorrelation Function and Mutual Information from Short Experimental Time Series
    Autorzy:
    Zduniak, A.
    Łusakowski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1932093.pdf
    Data publikacji:
    1995-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    05.45.+b
    Opis:
    A nonlinear dynamics of self-generated current oscillations in semi-insulating GaAs was studied by the reconstruction of an attractor from a short (14500 points) time series. Two methods of choosing of a time constant (τ) for this reconstruction are compared. One of them assumes τ to be an argument of the first zero of the autocorrelation function and the other takes τ as an argument of the first minimum of the mutual information. It is shown that for periodic oscillations both methods are equivalent, but for chaotic ones only the mutual information gives a time constant which does not depend on a time series used for calculations.
    Źródło:
    Acta Physica Polonica A; 1995, 87, 1; 257-260
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Electron Temperature in Semi-Insulating GaAs for Low Electric Fields
    Autorzy:
    Zduniak, A.
    Łusakowski, J.
    Nowak, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/1923732.pdf
    Data publikacji:
    1992-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    72.20.Ht
    Opis:
    Heating of electrons by electric fields smaller than that required for generation of domain oscillations was investigated in samples of EL2-rich semi-insulating GaAs. Current-voltage characteristics were measured as a function of temperature between 268 K and 330 K. They exhibit a sublinear shape which is interpreted as a result of an enhanced electron capture on the EL2. The capture rate and the electron temperature as a function of the electric field was determined. A fitting procedure gave the value of electron capture cross-section on the EL2 to be 2.7 × 10$\text{}^{-13}$ cm$\text{}^{2}$ which agrees with literature data.
    Źródło:
    Acta Physica Polonica A; 1992, 82, 5; 777-780
    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:
    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:
    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:
    Electrical and Structural Properties of Ohmic Contacts to n-Type and High Resistivity CdTe
    Autorzy:
    Kamińska, E.
    Piotrowska, A.
    Guziewicz, M.
    Gierlotka, S.
    Papis, E.
    Łusakowski, J.
    Szadkowski, K.
    Kwiatkowski, S.
    Dietl, T.
    Grabecki, G.
    Jaroszyński, J.
    Karczewski, G.
    Zakrzewski, A. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/1873052.pdf
    Data publikacji:
    1995-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    73.40.Ns
    Opis:
    The interaction between CdTe and In during the formation of an ohmic contact has been investigated. Emphasis is placed on the study of the effect of thermally induced sublimation of cadmium on electrical properties of contacts. Presented results prove the effectiveness of cap annealing and rapid thermal processing in fabrication of improved ohmic contacts with limited Cd losses during the contacting procedure.
    Źródło:
    Acta Physica Polonica A; 1995, 87, 2; 411-414
    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
      Wyświetlanie 1-27 z 27

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