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Wyświetlanie 1-12 z 12
Tytuł:
Cooper Pair with Nonzero Momentum in System with Spin Dependent Mass of Quasiparticles
Autorzy:
Kaczmarczyk, J.
Spałek, J.
Powiązania:
https://bibliotekanauki.pl/articles/2047323.pdf
Data publikacji:
2007-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.24.+q
71.10.Li
Opis:
We consider a single Cooper pair with the spin dependent quasiparticle masses, with and without applied magnetic field. Such situation takes place for the strongly correlated electron systems, where a relatively strong Hubbard interaction differentiates the quasiparticle states in the majority- and the minority-spin subbands. In that situation, the two spin subbands in an applied magnetic field are not only shifted one with respect to the other, but also distorted differently, which results from the electronic correlations. Under these circumstances, the fermionic particles composing the Cooper pair, are quantum mechanically distinguishable. In result, the Cooper pair has a nonzero momentum (i.e. produces a stationary current in a similar manner as electron in the Bloch state), and there exists a critical value of the attractive interaction, below which the bound Cooper-pair state is not formed. The presence of the applied field (included via the Zeeman term) does not alter the picture qualitatively. Importance of these results for the formation of the Fulde-Ferrell-Larkin-Ovchinnikov phase in strongly correlated systems is mentioned.
Źródło:
Acta Physica Polonica A; 2007, 111, 4; 595-602
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical Response of La$\text{}_{1-x}$MnO$\text{}_{3}$/Al$\text{}_{2}$O$\text{}_{3}$ Films
Autorzy:
Babonas, G.-J.
Reza, A.
Szymczak, R.
Baran, M.
Fröhlich, K.
Jasutis, V.
Diduszko, R.
Powiązania:
https://bibliotekanauki.pl/articles/2035658.pdf
Data publikacji:
2003-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.66.Li
75.70.Ak
Opis:
La$\text{}_{1-x}$MnO$\text{}_{3}$ films grown by metal organic chemical vapor deposition technique on r-plane cut Al$\text{}_{2}$O$\text{}_{3}$ substrates were investigated. The change of the optical response over the La$\text{}_{1-x}$MnO$\text{}_{3}$/Al$\text{}_{2}$O$\text{}_{3}$ sample surface was investigated along with the temperature dependence of magnetization. The mostly pronounced difference in the spectra of dielectric function occurred in the region of the d-d transitions of Mn-ions. The changes in the optical spectra and magnetic properties were correlated to the structural features of thin film.
Źródło:
Acta Physica Polonica A; 2003, 103, 1; 77-83
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electromagnetic Response of the BCS Superconductor: Flow Equation Approach
Autorzy:
Zapalska, M.
Domański, T.
Powiązania:
https://bibliotekanauki.pl/articles/1431495.pdf
Data publikacji:
2012-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.Fg
71.10.Li
05.10.Cc
Opis:
We address the linear response for superconductors using the non-perturbative technique based on the continuous unitary transformation. We discuss how this method rigorously reproduces the standard BCS solution and point out how such result can be generalized to the case of electron systems with strong pairing fluctuations and in presence of the nonequilibrium phenomena.
Źródło:
Acta Physica Polonica A; 2012, 121, 4; 854-857
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
One-Electron Excitations vs. Collective Excitations in the 1D Falicov-Kimball Model with Hund Coupling at Half Filling
Autorzy:
Wrzodak, J.
Lemański, R.
Powiązania:
https://bibliotekanauki.pl/articles/1537078.pdf
Data publikacji:
2010-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
71.10.Li
75.10.-b
Opis:
The Falicov-Kimball model enriched with Ising-type Hund coupling between spins of itinerant electrons and magnetic ions is studied exactly on finite 1D rings. At half filling (one electron per site) and for the density of magnetic ions equal to 1/2 it is shown that many-electron collective excitations coupled to spin reorientations of the magnetic ions have much lower energy than single electron excitations. This property is caused by energy gaps formed at the Fermi levels in one-electron energy spectra of all relevant magnetic configurations of the ions. Consequently, low temperature properties of the system are not driven by one-particle, elementary electron excitations but many-particle collective excitations, where both electrons and spins of magnetic ions are involved. In addition, it is shown that many-body excitation spectra derived both from spin fluctuations and from charge fluctuations have a regular structure.
Źródło:
Acta Physica Polonica A; 2010, 118, 2; 366-368
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of Terahertz Emission from Surfaces of Cu(InGa)Se_2 Layers
Autorzy:
Koroliov, A.
Arlauskas, A.
Balakauskas, S.
Šoliūnas, M.
Maneikis, A.
Krotkus, A.
Šetkus, A.
Tamošiūnas, V.
Powiązania:
https://bibliotekanauki.pl/articles/1399106.pdf
Data publikacji:
2013-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.66.Li
88.40.jn
77.55.hf
Opis:
In this contribution, we report on investigations of THz emission from $Cu(In,Ga)Se_2$ layers, deposited from a single copper-deficient sputtering target. Emission from $Cu(In,Ga)Se_2$ layer surface and from multilayer structure with transparent ZnO layers were studied. It was determined that additional undoped ZnO layer reduces the amplitude of THz emission, while additional n-type ZnO layers increase the emission amplitude again. This effect can be attributed to stronger electric field in the heterostructure between p-type $Cu(In,Ga)Se_2$ and n-type ZnO layers.
Źródło:
Acta Physica Polonica A; 2013, 124, 5; 846-848
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural and Optoelectronic Properties of In-Zn-S sprayed Layers
Autorzy:
Lazzez, S.
Boubaker, K.
Ben Nasrallah, T.
Amlouk, M.
Belgacem, S.
Mnari, M.
Chtourou, R.
Powiązania:
https://bibliotekanauki.pl/articles/1812052.pdf
Data publikacji:
2008-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.60.Dp
78.66.Li
78.30.Am
Opis:
In this work, In-Zn-S thin layers were prepared using the spray pyrolysis technique on glass substrates at 320°C. The molar ratio between zinc and indium $x=[Zn^{2+}]//[In^{3+}]$ was varied in 0-0.4 domain whereas $[S^{2-}]//[In^{3+}]$ one was taken constant equal to 2. The atomic composition was carried out with the atomic absorption. The structural study of all layers via X-ray diffraction and atomic force microscopy shows that the layer, obtained using x=0 is formed by binary material $In_2S_3$ with a principal orientation along (400). When the composition increases the same study depicts the presence of other materials such as ZnO, ZnS, and $ZnIn_2S_4$. On the contrary, for x=0.4, the film is mainly formed by the ternary compound $ZnIn_2S_4$ which crystallizes in cubic phase. Moreover, the optical analysis via the transmittance, reflectance as well as the photocurrent reveals that the band gap energy $E_g$ increases slightly as a function of the x composition ($E_g$ varies from 2.6 to 2.9 eV).
Źródło:
Acta Physica Polonica A; 2008, 114, 4; 869-880
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pseudogap and Other Precursor Signatures in the Systems with Local Fermion Pairs
Autorzy:
Domański, T.
Powiązania:
https://bibliotekanauki.pl/articles/2038382.pdf
Data publikacji:
2004-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.Mn
71.10.Li
03.75.Kk
Opis:
We consider precursor effects of the superconducting order which possibly show up in the normal state of high temperature superconducting materials. The local pairs of electrons or holes are formed there well above the transition temperature T$\text{}_{c}$. Due to strong quantum fluctuations the single particle density of states can be partly depleted near the Fermi energy leading to the pseudogap. We claim that this feature should go hand in hand with emergence of the Bogoliubov-type quasiparticles. In the normal state they are expected to be damped and acquire the long lifetime upon passing T$\text{}_{c}$. These Bogoliubov-type quasiparticles may nevertheless become correlated on a finite spatial and temporal scale. We discuss how such short-range pair correlations can be detected experimentally.
Źródło:
Acta Physica Polonica A; 2004, 106, 5; 553-560
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Relative Reflection Difference as a Method for Measuring the Thickness of the Exfoliated MoSe₂ Layers
Autorzy:
Łempicka, K.
Norowski, K.
Grzeszczyk, M.
Król, M.
Lekenta, K.
Babiński, A.
Piętka, B.
Szczytko, J.
Powiązania:
https://bibliotekanauki.pl/articles/1033778.pdf
Data publikacji:
2017-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.20.dd
78.20.Ci
78.30.-j
78.66.Li
Opis:
We propose a method for measuring the thickness of the exfoliated MoSe₂ layers deposited on Si/SiO₂ substrate, based on the reflectance measurements performed with laser light illumination at two different wavelengths: red and green from confocal microscope at room temperature. We demonstrate the correlation between the number of layers in a flake and the value of its relative reflection difference. We applied the transfer matrix method to calculate the reflectivity and verify our experimental results. The approach proposed by us allows for fast and automatic verification of the exfoliated MoSe₂ layers thickness on large areas of the substrate.
Źródło:
Acta Physica Polonica A; 2017, 132, 2; 316-318
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical and Structural Studies of Sol-Gel Deposited Nanostructured CdO Thin Films: Annealing Effect
Autorzy:
Abdolahzadeh Ziabari, A.
Ghodsi, F.
Powiązania:
https://bibliotekanauki.pl/articles/1493680.pdf
Data publikacji:
2011-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.Ci
78.66.Li
78.67.-n
81.20.Fw
Opis:
Nanocrystalline CdO thin films were prepared by sol-gel dip-coating method using a different solution. The as-deposited films were subjected to drying temperature of 120° in air. The prepared films were annealed in different temperatures of 200, 300 and 400°C. The characterization of samples was carried out by X-ray diffraction, scanning electron microscopy and UV-VIS spectroscopy. Results show that the samples are polycrystalline in nature and the crystallinity of the films improves with temperature. The average grain size is in the range of 19-34 nm. It was observed that the optical parameters of the films were affected by annealing temperature.
Źródło:
Acta Physica Polonica A; 2011, 120, 3; 536-540
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Confocal Microscope Studies of $MoS_{2}$ Layer Thickness
Autorzy:
Grzeszczyk, M.
Gołasa, K.
Piętka, B.
Babiński, A.
Szczytko, J.
Powiązania:
https://bibliotekanauki.pl/articles/1377207.pdf
Data publikacji:
2014-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.Ci
63.20.dd
78.30.-j
78.66.Li
Opis:
We have been studying micro-luminescence of various exfoliated $MoS_{2}$ flakes using a confocal microscope. A crucial issue is to determine thickness of the investigated layer. The common way - using atomic force microscopy, electron microscopy or the Raman spectroscopy - requires moving the sample out from the confocal microscope experimental setup and looking for a particular exfoliated flake hidden among thousands of others. In order to preliminarily determine thickness of investigated layers we have performed a study on optical reflectivity and compared the results with the Raman spectroscopy investigations. In this way we were able to calibrate our experimental setup. Optical measurements are much faster than the Raman spectroscopy and can give a good estimation of $MoS_{2}$ thickness.
Źródło:
Acta Physica Polonica A; 2014, 126, 5; 1207-1208
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Resonant Two-Electron Pairs in a Simple Cubic Lattice
Autorzy:
Bak, M.
Powiązania:
https://bibliotekanauki.pl/articles/1374452.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
31.15.xh
71.10.Li
71.55.-i
03.65.Ge
02.30.Zz
Opis:
The properties of resonant two-electron pairs are examined in three-dimensional simple cubic extended Hubbard tUW model, in s- and d- symmetry channels, in the limit of empty lattice. Lattice Green function technique is applied to calculate the scattering amplitude by means of matrix for any energy in the band on ΓR line within the Brillouin zone. The analysis shows the persistence of resonant states even for Coulomb interactions so weak that the equation for the resonant states is not formally fulfilled. The difference in behavior of resonances controlled by on-site and intersite Coulomb interactions is found. The ranges of applicability of approximate formula for the actual position of resonant peak and its width are shown.
Źródło:
Acta Physica Polonica A; 2014, 126, 4a; A-63-A-69
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Majorana Fermions on Andreev Spectroscopy of Multiband Topological Superconductors
Autorzy:
Silva, A.
Araújo, M.
Sacramento, P.
Powiązania:
https://bibliotekanauki.pl/articles/1402577.pdf
Data publikacji:
2015-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.Fd
71.10.Pm
71.10.Li
73.20.-r
74.45.+c
74.20.Rp
74.70.-b
Opis:
We introduce a model for a multiband topological superconductor with two orbitals per lattice site, in two spatial dimensions. Concentrating on the Andreev reflection problem, the appropriate wave function matching conditions for an interface with a normal single-band metal were previously derived in the framework of a quantum waveguide theory. This theory retrieves the correct number of Majorana fermion states as predicted by the topological index. We obtain the differential conductance as a function of bias voltage, which displays the contribution of the Majorana fermions. Interface disorder is also considered. By varying band structure parameters, topological transitions can be induced, whereby the number of the Majorana modes varies. We calculate the effect of such transitions on the differential conductance.
Źródło:
Acta Physica Polonica A; 2015, 128, 2; 210-212
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-12 z 12

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