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Wyszukujesz frazę "74.40.-n" wg kryterium: Temat


Wyświetlanie 1-7 z 7
Tytuł:
On Realization of the Bose-Einstein Condensates and Quantum Superfluids
Autorzy:
Domański, T.
Powiązania:
https://bibliotekanauki.pl/articles/1536541.pdf
Data publikacji:
2010-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.-z
74.20.Mn
74.40.-n
Opis:
The purpose of this work is twofold. In the first part we describe superfluidity/superconductivity as an emergent phenomenon resulting from two-body correlations in presence of the Bose-Einstein condensation of particles. We briefly discuss the underlying mechanism for bosons as well as fermion pairs and illustrate various realizations of superfluidity emphasizing the recent examples. In the second part we study the glassy liquid of incoherent pairs which might exist above the transition temperature $T_{c}$ in the underdoped regime of cuprate superconductors. In particular, we explore the angular variation of pseudogap within two-dimensional version of the boson-fermion model using for a quantitative analysis the projective method. We find that above $T_{c}$ the pseudogap closes first near the nodal areas restoring there pieces (arcs) of the Fermi surface whereas remaining parts of the large Fermi surface around the antinodal points are still absent due to incoherent pairs. Upon increasing temperature the length of the Fermi arcs enlarges because the superconducting correlations are gradually suppressed. An intriguing death of Fermi surface can thus be closely related to the Bogoliubov quasiparticles whose existence in the pseudogap state has been predicted by us and confirmed recently by the angle resolved photoemission spectroscopy measurements on $Bi_2Sr_2CaCu_2O_8$ and $La_{1.895}Sr_{0.105}CuO_4$ compounds.
Źródło:
Acta Physica Polonica A; 2010, 118, 2; 204-211
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Light-Emitting Diode Degradation and Low-Frequency Noise Characteristics
Autorzy:
Šaulys, B.
Matukas, J.
Palenskis, V.
Pralgauskaitė, S.
Kulikauskas, G.
Powiązania:
https://bibliotekanauki.pl/articles/1505229.pdf
Data publikacji:
2011-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.70.+m
74.40.-n
85.30.-z
85.60.Jb
Opis:
Comprehensive investigation of phosphide-based red and nitride-based blue light-emitting diodes characteristics and physical processes that take place in device structure during aging has been carried out. Analysis of noise characteristics (the emitting-light power and the LED voltage fluctuations, also their cross-correlation factor) shows that investigated LEDs degradation is caused by defects that lead to the leakage current and non-radiating recombination increase in the active region or its interfaces. Appearance of the defects first of all manifests in noise characteristics: intensive and strongly correlated $1//f^{α}$ type optical and electrical fluctuations come out.
Źródło:
Acta Physica Polonica A; 2011, 119, 4; 514-520
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical and Electrical Noise Characteristics of Side Emitting LEDs
Autorzy:
Šaulys, B.
Kornijčuk, V.
Matukas, J.
Palenskis, V.
Pralgauskaitė, S.
Glemža, K.
Powiązania:
https://bibliotekanauki.pl/articles/1506222.pdf
Data publikacji:
2011-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.70.+m
74.40.-n
85.60.Jb
Opis:
Low frequency noise characteristics of nitride based blue side emitting diodes have been investigated. It is shown that investigated devices distinguish by $1//f^α$-type optical and electrical fluctuations caused by various generation-recombination processes through defects formed generation-recombination centers. At higher frequencies optical shot noise due to random photon emission prevails $1//f^α$-type spectrum. The results have shown that low frequency optical and electrical noises are strongly correlated at small current region, but at higher forward current not correlated noise components dominate. Lenses and secondary optics of the investigated devices do not influence output light.
Źródło:
Acta Physica Polonica A; 2011, 119, 2; 244-246
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of Resistive Superconducting Transition of Thallium Based Superconductors
Autorzy:
Woch, W.
Zalecki, R.
Chrobak, M.
Kołodziejczyk, A.
Gritzner, G.
Powiązania:
https://bibliotekanauki.pl/articles/1431253.pdf
Data publikacji:
2012-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.40.n
74.20.De
74.25.Ha
Opis:
A width and shape of resistive transition as well as thermal fluctuations of the thallium based superconductors were analyzed theoretically. The applied magnetic field widens the resistive transition according to the following formula: $ΔT=CH^{m}+ΔT_{0}$. The exponent m fluctuates around 2/3 and depends on vortex structure and strength of the pinning force. The shape of the resistive transition was fitted by two models: the first one based on Ambegaokar-Halperin theory and the other one based on Anderson-Kim theory expressed by the exponential formula. Critical fluctuations were analyzed on the basis of magnetoresistance measurements results. The critical exponents have been calculated above the critical temperature $T_{c}$ as well as for temperatures close to the zero resistance critical temperature.
Źródło:
Acta Physica Polonica A; 2012, 121, 4; 789-795
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal Fluctuations of $(Tl_{0.5}Pb_{0.5})Sr_2(Ca_{0.9}Gd_{0.1})Cu_2O_{z}$ Bulk Superconductor
Autorzy:
Woch, W.
Chrobak, M.
Kołodziejczyk, A.
Gritzner, G.
Powiązania:
https://bibliotekanauki.pl/articles/1426876.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.40.-n
74.20.De
74.25.Ha
Opis:
We report on the critical fluctuations from the magnetoresistance measurements in polycrystalline $(Tl_{0.5}Pb_{0.5})Sr_2(Ca_{0.9}Gd_{0.1})Cu_2O_{z}$ superconductor. The critical exponents have been calculated above the critical temperature $T_{c}$ as well as in the temperatures interval close to the zero resistance critical temperature. Above $T_{c}$ only Gaussian fluctuations have been observed in a three-dimensional fluctuating system. Additionally, far above $T_{c}$ the applied magnetic field induces the crossover from 3D to 2D fluctuating system. At the temperatures range close to the zero critical temperature the properties of the weak links are dominating and the fluctuating phase in each grain becomes long-range ordered as a consequence of the activation of weak links between grains.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1059-1062
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal Fluctuations in YBCO Thin Film on MgO Substrate
Autorzy:
Chrobak, M.
Woch, W.
Szwachta, G.
Zalecki, R.
Gondek, Ł.
Kołodziejczyk, A.
Kusiński, J.
Powiązania:
https://bibliotekanauki.pl/articles/1374789.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.78.-w
74.40.-n
74.62.-c
Opis:
The c-axis orientation $YBa_2Cu_3O_δ$ thin film was prepared directly on MgO substrate by the pulse laser deposition. The thickness of the film was 170 nm. The superconducting critical temperature was $T_{c50%}$=89 K and the width of superconducting transition was Δ T= 1.6 K. Temperature dependence of the critical current of the film was obtained from the temperature dependences of the imaginary part of the AC susceptibility using the Bean model. The critical current density was $J_{c}$=1.2×$10^7$ A/$cm^{2}$ at 77 K in the self field. The critical exponents were calculated for several values of the DC applied magnetic field using the temperature dependences of magnetoresistivity. The thermal fluctuations in vicinity of the critical temperature were analysed.
Źródło:
Acta Physica Polonica A; 2014, 126, 4a; A-88-A-91
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal Fluctuations of Bismuth Based 1G Tape
Autorzy:
Chrobak, M.
Woch, W.
Zalecki, R.
Kołodziejczyk, A.
Powiązania:
https://bibliotekanauki.pl/articles/1385435.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.78.-w
74.40.-n
74.62.-c
Opis:
The thermal fluctuations of bismuth based commercial 1G tape were studied near the critical temperature $T_{c}$=110.2 K. The detailed analysis of the temperature dependence of resistivity measurements was made in the temperature region from the zero resistance critical temperature up to 300 K. The thermal fluctuations of conductivity were analysed using the Aslamazov-Larkin microscopic approach and the critical exponents were calculated close to the transition temperature.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 306-308
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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