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Tytuł:
Magnetic Susceptibility and Charge State of Gd Impurity in Pb$\text{}_{1-x}$Sn$\text{}_{x}$Te⟨Gd⟩ Crystals
Autorzy:
Zayachuk, D. M.
Ivanchuk, R. D.
Kempnyk, V. I.
Mikityuk, V. I.
Powiązania:
https://bibliotekanauki.pl/articles/1952432.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
Opis:
The effective magnetic momentum p$\text{}_{eff}$ of Gd-impurities in the Pb$\text{}_{1-x}$Sn$\text{}_{x}$Te⟨Gd⟩ crystals as a function of crystal composition x with 0 ≤ x ≤ 0.25 is studied. It is shown that with the increase in tin content in the crystals from 0 to 0.15, p$\text{}_{eff}^{2}$(Gd) increases slowly from 37 to 43. Then p$\text{}_{eff}^{2}$(Gd) increases abruptly to 63 value when x = 0.16±0.01. For subsequent increase x ≥ 0.17 p$\text{}_{eff}^{2}$(Gd) remains constant at 63. Possible reasons of observed changes of p$\text{}_{eff}$(Gd) and possible mechanisms of influence of the Pb$\text{}_{1-x}$Sn$\text{}_{x}$Te crystal field on the effective magnetic momentum value of Gd-impurities in the crystals under study are analysed.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 985-988
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Annealing Study of Al/GaSb Contact with the Use of Doppler Broadening Technique
Autorzy:
Wang, H. Y.
Weng, H. M.
Ling, C. C.
Ye, B. J.
Zhou, X. Y.
Han, R. D.
Powiązania:
https://bibliotekanauki.pl/articles/2043365.pdf
Data publikacji:
2005-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
68.35.Ct
73.40.Sx
Opis:
Using a monoenergetic positron beam, annealing study of the Al/n-GaSb system was performed by monitoring the Doppler broadening of the annihilation radiation as a function of the positron implanting energy. The S-parameter against positron energy data was successfully fitted by a three-layer model (Al/interface/GaSb). The annealing out of the open volume defects in the polycrystalline Al layer was revealed by the decrease in the S-parameter and the increase in the effective diffusion length of the Al layer. For the as-deposited samples, a 5 nm interfacial region with S-parameter larger than those of the Al overlayer and the bulk was identified. After the 400ºC annealing, this interfacial region extends to over 40 nm and its S-parameter dramatically drops. This is possibly due to the new phase formation at the interface. Annealing behaviors of S$\text{}_{B}$ and L$\text{}_{+,B}$ of the GaSb bulk showed the annealing out of positron traps (possibly the V$\text{}_{Ga}$-related defect) at 250ºC. However, a further annealing at 400ºC induces the formation of positron traps, which are possibly of another kind of V$\text{}_{Ga}$-related defect and the positron shallow trap GaSb antisite.
Źródło:
Acta Physica Polonica A; 2005, 107, 5; 874-879
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Polaron Formation in Semimagnetic Semiconductor Heterostructures
Autorzy:
Yakovlev, D. R.
Powiązania:
https://bibliotekanauki.pl/articles/1947113.pdf
Data publikacji:
1996-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.Ls
71.35.+z
75.50.Rr
Opis:
We present a survey of experimental and theoretical studies of exciton magnetic polarons in semimagnetic semiconductor epilayers, quantum wells and superlattices. The emphasis is on dynamical aspects of magnetic polaron formation in systems of different dimensionality.
Źródło:
Acta Physica Polonica A; 1996, 90, 4; 703-714
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin Wave Dynamics of 2D and 3D Heisenberg Antiferromagnets
Autorzy:
Cowley, R.
Tennant, D.
Coldea, R.
Powiązania:
https://bibliotekanauki.pl/articles/1810280.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Gb
75.50.Ee
61.12.Ex
Opis:
The excitations of the 2D Heisenberg antiferromagnet, $Rb_2MnF_4$, were studied using neutron scattering techniques with the MAPS spectrometer at the ISIS facility of Rutherford Appleton Laboratory. Measurements were made of the magnetic excitations over the whole 2D Brillouin zone at 6 temperatures below the ordering temperature of 38 K and 6 temperatures above. It was found that the excitations were well defined if their wave vectors were larger than the inverse correlation length and were overdamped if the wave vectors of the excitations were smaller than the inverse correlation length. In more detail we have compared our experimental results with the results of classical simulations and the results gave a very adequate description of the experimental results except at the lowest temperature where the form of the dispersion relation was correct but the energies of the excitations were in error. Nevertheless, classical simulations do provide an efficient and easily implemented methodology for modelling the excitations in the Heisenberg magnets. The damping of the excitations was experimentally found to follow a $T^2$ behaviour over all wave vector and energy scales. This is in agreement with the classical simulations but inconsistent with analytic theories of the damping for the 2D Heisenberg model and in particular does not agree with hydrodynamic behaviour or dynamic scaling. The result is similar to that found in 3D Heisenberg systems and suggests that more analytic theory is needed to explain the experimental results for both 2D and 3D Heisenberg magnets.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 19-24
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Size Dependent Acoustical Properties of bcc Metal
Autorzy:
Yadav, R. R.
Pandey, D. K.
Powiązania:
https://bibliotekanauki.pl/articles/2043375.pdf
Data publikacji:
2005-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.20.Dc
62.65.+k
63.20.Kr
Opis:
The ultrasonic attenuation is evaluated at 300 K along [100], [110], and [111] directions for the characterization of bcc metal Ta. The size of the metal is considered in nanorange. Ultrasonic velocity, Grüneisen parameter and acoustic coupling constant that depend on second and third order elastic constants are calculated for determination of ultrasonic attenuation coefficient. Second and third order elastic constants of the bcc metal Ta at nanoscale at 300 K are also calculated starting with only two basic parameters. For the information about defects at nanoscale, the dislocation drag coefficients are calculated for the metal at different size along [100] orientation. The ultrasonic attenuation increases with the size of material as the size variation of the thermal conductivity and the thermal relaxation time. There is significant increase in the attenuation up to 150 nm.
Źródło:
Acta Physica Polonica A; 2005, 107, 6; 933-946
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quasistationary Electron States for CdTe/ZnTe/CdTe Open Spherical Quantum Dots
Autorzy:
Stojanović, D.
Kostić, R.
Powiązania:
https://bibliotekanauki.pl/articles/1537875.pdf
Data publikacji:
2010-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.63.Kv
73.22
Opis:
The energy spectra of an electron in open spherical quantum dot (QD) within the effective mass approximation (EMA) and rectangular potential model is presented. Energy structure of quantum dots is important because of their possible applications in electronic and optoelectronic devices. For proper description and interpretation of tunneling processes knowledge of resonant states of quantum dots is necessary. Energy values depend on parameter like size of system and spatial composition. The lifetimes of the quasistationary states are computed within the framework of the scattering S-matrix method. It is shown how core radius and barrier thickness for the CdTe/ZnTe/CdTe example influence electron states and their lifetimes.
Źródło:
Acta Physica Polonica A; 2010, 117, 5; 768-771
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multi-Color Emission in Quantum-Dot-Quantum-Well Semiconductor Heteronanocrystals
Autorzy:
Kostić, R.
Stojanović, D.
Powiązania:
https://bibliotekanauki.pl/articles/1795612.pdf
Data publikacji:
2009-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.21.La
78.67.Bf
Opis:
We present calculation results of multi-color spontaneous emission from quantum-dot-quantum-well semiconductor heteronanocrystals. Our theoretical results explain experimental results of onion-like spherical system similar to: CdSe (core), ZnS (shell), CdSe (shell) spherical quantum dots surrounded by ZnS. We demonstrate influence of shell thickness to exciton localization in distinct layers of heteronanocrystals. Multi-color emission of such heterosystem is determined by l=0, n=1 state localization in CdSe core and by l=0, n=2 state localization in CdSe shell.
Źródło:
Acta Physica Polonica A; 2009, 116, 4; 598-602
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermodynamic Critical Magnetic Field for Chlorine Halide Superconductor at High Pressure
Autorzy:
Szczęśniak, D.
Szczęśniak, R.
Powiązania:
https://bibliotekanauki.pl/articles/1382363.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.Fg
74.25.Bt
74.62.Fj
Opis:
At present, hydrides are considered as a one of the most interesting high-temperature superconductors with the classical electron-phonon pairing mechanism. In the present paper, we have analyzed the dependence of the thermodynamic critical magnetic field $(H_c)$ on the temperature for the chlorine halide superconductor. The calculations have been made in the framework of the Eliashberg formalism for the following pressure values: $p_{1}$=320 GPa and $p_{2}$=360 GPa. We have shown that $H_c$ increases strongly with the increase of the pressure: $[H_c(0)]_{p_{2}}$/$[H_c(0)]_{p_{1}}$= 1.43. Furthermore, the dimensionless ratio: $R_{H}$ ≡ $T_cC^{N}(T_c)$/$H_c^{2}(0)$, where $T_c$ and $C^{N}$ denote the critical temperature and the specific heat of the normal state, differs from the value predicted by the Bardeen-Cooper-Schrieffer theory. In particular: $[R_{H}]_{p_{1}}$=0.166 and $[R_{H}]_{p_{2}}$=0.158.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 344-345
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Report on Foundation and Organization of Econophysics Graduate Courses at Faculty of Physics of University of Warsaw and Department of Physics and Astronomy of the Wrocław University
Autorzy:
Kutner, R.
Grech, D.
Powiązania:
https://bibliotekanauki.pl/articles/1812237.pdf
Data publikacji:
2008-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
01.10.Hx
89.65.Gh
01.40.Di
01.10.-m
Opis:
Two different, working examples of organization of econophysics graduate courses at the Faculty of Physics, University of Warsaw and the Department of Physics and Astronomy of the Wrocław University are considered. In the first example we have a system where the interdisciplinary, econophysical education begins only after three years study of physics. Within this system the M.Sc. as well as Ph.D. theses in econophysics are conducted only at the Faculty of Physics. In the second example the B.Sc. theses in econophysics are accomplished in the Department of Physics and Astronomy again after three years study but higher degrees can be prepared either in physics in the Institute of Theoretical Physics or in economy in the Institute of Economical Sciences. M.Sc. and Ph.D. theses can also be conducted. For both examples, the graduate students of econophysics are obliged to participate in traditional (typical) economical lectures and trainings which are offered them by economical departments while lectures and trainings (tutorials and/or laboratory classes) in econophysics are offered them by physics departments themselves. Thus Poland is one of a few countries, where so modern interdisciplinary knowledge is systematically offered to students.
Źródło:
Acta Physica Polonica A; 2008, 114, 3; 637-647
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Transport through the Double-Dot System
Autorzy:
Świrkowicz, R.
Sztenkiel, D.
Powiązania:
https://bibliotekanauki.pl/articles/2038086.pdf
Data publikacji:
2004-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.Hr
72.15.Qm
72.25.-b
73.23.Hk
Opis:
Electron tunnelling through two quantum dots in series is theoretically studied. A limit of intermediate coupling between the dots is considered. The non-equilibrium Green function formalism is used to calculate electric current and mean number of electrons accumulated on the dots. Lesser and retarded Green functions are calculated in the Hartree-Fock approximation with the use of the equation of motion method. Current flowing through the system calculated in dependency on gate voltages shows two resonant peaks, each peak with two additional shoulders. I-V characteristics and differential conductance in a resonance and out of resonance cases are calculated and discussed.
Źródło:
Acta Physica Polonica A; 2004, 105, 6; 523-528
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Transport through Double Quantum Dot: from SU(4) Kondo to SU(2) Symmetry
Autorzy:
Sztenkiel, D.
Świrkowicz, R.
Powiązania:
https://bibliotekanauki.pl/articles/2047706.pdf
Data publikacji:
2007-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.63.Kv
72.15.Qm
73.40.Gk
73.23.Hk
Opis:
Electron transport across two capacitively coupled quantum dots in a parallel geometry is theoretically studied in the non-linear response regime with spin and orbital degrees of freedom taken into account and the Kondo effect induced by on-site and inter-dot Coulomb correlations is analyzed. For a system with each dot symmetrically coupled to a separate set of electrodes a well-defined spin and orbital contributions to zero-bias Kondo resonance are obtained. The Kondo peak splits if spin and/or orbital degeneracies are removed. A suppression of the orbital Kondo anomaly due to orbital asymmetry and channel mixing effects is discussed.
Źródło:
Acta Physica Polonica A; 2007, 112, 2; 387-393
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Transport through Double Quantum Dots with Interdot Coulomb Repulsion
Autorzy:
Sztenkiel, D.
Świrkowicz, R.
Powiązania:
https://bibliotekanauki.pl/articles/2047016.pdf
Data publikacji:
2006-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.23.-b
73.21.La
73.23.Hk
Opis:
Electron transport through a system of two quantum dots connected in series is studied theoretically with the use of non-equilibrium Green function formalism based on the equation of motion method. Each dot is described by the one-level Anderson Hamiltonian and interdot Coulomb interactions in the form of the Hubbard-like term are taken into account. The electric current and occupation numbers are calculated with the use of two different approaches. The results of the methods are compared and discussed in detail. Strong asymmetry of I-V characteristics with respect to bias voltage reversal are obtained when energy levels of the dots are not aligned.
Źródło:
Acta Physica Polonica A; 2006, 110, 3; 389-394
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Transport through Double Quantum Dot System with Inter-Dot Coulomb Interaction
Autorzy:
Sztenkiel, D.
Świrkowicz, R.
Powiązania:
https://bibliotekanauki.pl/articles/2047295.pdf
Data publikacji:
2007-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.23.-b
73.21.La
73.23.Hk
Opis:
A theoretical approach to a problem of electron transport through double quantum dot systems based on non-equilibrium Green function formalism using equation of motion method is presented. I-V characteristics and differential conductance are calculated and discussed in detail in the intermediate regime with tunneling rate between the quantum dots comparable to coupling constants with external electrodes. Effects of inter-dot Coulomb correlations are studied for various values of interaction parameter U. It is shown that the interaction influences transport properties in a pronounced way and apart from the simple Coulomb blockade additional effects can be obtained. When energy levels of two quantum dots are not aligned, the asymmetry in conductance characteristics is closely related to a voltage dependence of population numbers in both quantum dots. For a one bias polarization electrons are well localized in quantum dots in a low voltage region, whereas for the opposite one they are partly delocalized.
Źródło:
Acta Physica Polonica A; 2007, 111, 3; 361-372
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Phase Transformations on Incipient Plasticity of Si-Nanospheres
Autorzy:
Chrobak, D.
Nowak, R.
Powiązania:
https://bibliotekanauki.pl/articles/1033040.pdf
Data publikacji:
2017-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.20.-x
62.50.-p
64.70.kg
Opis:
Our finding of the current spike effect highlighted for the first time in 2009 offers an enhanced understanding of the link between nanoscale mechanical deformation and electrical behavior, and ultimately suggests key advances in unique phase-change applications in future electronics. Certainly, crystal imperfections affect the properties of the nanoparticles themselves, e.g., their biocompatibility and biodegradability. The potential role of dislocations having a profound impact on the use of Si nanoparticles was largely overlooked, since plastic deformation of bulk Si is dominated by amorphization and phase transformations. Here we show an effect of bulk → nanoparticle transition (deconfinement) on incipient plasticity of Si-nanovolume. Our results provide a fresh insight into the dilemma concerning dislocation or phase transformation origin of nanoscale plastic deformation of semiconductor nanoobjects.
Źródło:
Acta Physica Polonica A; 2017, 131, 5; 1318-1331
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hyperbolic Icosahedral Tilings by Buckyballs
Autorzy:
Lück, R.
Frettlöh, D.
Powiązania:
https://bibliotekanauki.pl/articles/1203218.pdf
Data publikacji:
2014-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.20.-a
61.48.-c
61.50.Ah
61.44.Br
Opis:
Hyperbolic icosahedral tilings by Buckyballs with 4 or 8 Buckyballs sharing a vertex are considered as an example of tilings by Archimedean polyhedra. Representation requires Poincaré balls; colour symmetry may be derived by GAP. Colour symmetries preserving both rotation and reflection symmetry as well as only rotation symmetry are discussed.
Źródło:
Acta Physica Polonica A; 2014, 126, 2; 524-526
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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