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Wyświetlanie 1-10 z 10
Tytuł:
Electronic States of Collosal Magnetoresistive Manganites $La_{0.67}Pb_{0.33}Mn_{1-x}Fe_{x}O_{3}$ from Photoemission Spectroscopy
Autorzy:
Kowalik, M.
Zalecki, R.
Kołodziejczyk, A.
Powiązania:
https://bibliotekanauki.pl/articles/1538821.pdf
Data publikacji:
2010-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Lp
79.60.Bm
71.15.Ap
74.20.Mn
Opis:
The electron photoemission spectra of valence bands and core-level states of manganese perovskite $La_{0.67}Pb_{0.33}(Mn_{1-x}Fe_{x})O_{3}$ with x = 0, 0.01, 0.03, 0.06, 0.10 and 0.15 were measured by the X-ray and Ultraviolet Photoemission Spectroscopy (XPS and UPS) below and above the metal-insulator transition. From analysis of the Mn 2p core-level spectra the ratio $Mn^{3+}//Mn^{4+}$ was calculated as a function of the iron content. Comparison of the valence band spectrum with band structure calculations and with the high-resolution spectra measured at synchrotron radiation for Ca-, Ba- and Ce- substituted manganites revealed the strong hybridisation of Mn 3d and of O 2p states between -3 eV and -7 eV, and no estimated oxygen states between 0 eV and -2 eV where the Mn-3d states play a predominant role. The composition dependent insulating energy gaps were measured at room temperature. Reasons for the behaviour were discussed taking into account previous analysis of XPS/UPS spectra of other manganese perovskites.
Źródło:
Acta Physica Polonica A; 2010, 117, 2; 277-280
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Band Structure and Photoemission States of $La_{2//3}Pb_{1//3}MnO_3$
Autorzy:
Tokarz, W.
Kowalik, M.
Zalecki, R.
Kołodziejczyk, A.
Powiązania:
https://bibliotekanauki.pl/articles/1427488.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.-b
71.55.Ak
72.80.Ga
75.47.Lx
79.60.-i
Opis:
We present the theoretical study of electronic and magnetic properties in a manganese perovskite $La_{2//3}Pb_{1//3}MnO_3$. The calculations were carried out in frame of the first-principles density functional theory with the general gradient approximation using the WIEN 2K package. The P3c1 crystal structure was taken from the detailed X-ray diffraction data for the perovskite. The exact exchange energy was utilized for Mn d electrons. Density of states was determined by the modified tetrahedron method. As a result we get a valence band for the spin up and down density of states with the gap for the latter of 1.85 eV. We noticed that conduction band is mainly dominated by d spin up manganese electrons and $Mn (d_{xz}, d_{yz})$ states have twice larger contribution than $(d_{x^2 - y^2}, d_{xy})$. We attribute this to $Mn-O_6$ octahedral tilting. From the same reason $d_{3z^2 - r^2}$ state has no contribution to the density of states at the Fermi energy $(E_{F})$. Comparison of total density of states with the ultraviolet photoemission spectroscopy measurements shows similar features especially as far as the lead spectral intensity from the 6s electrons at about - 10 eV is concerned. The calculated total magnetic moment per formula unit is 3.66 $μ_{B}$, the measured one 3.48 $μ_{B}$/f.u.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1151-1153
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bismuth Valence in a $Tl_{0.7}Bi_{0.3}Sr_{1.6}Ba_{0.4}CaCu_{2}O_{y}$ Superconductor from X-Ray Photoemission Spectroscopy
Autorzy:
Zalecki, R.
Woch, W.
Kowalik, M.
Kołodziejczyk, A.
Gritzner, G.
Powiązania:
https://bibliotekanauki.pl/articles/1537186.pdf
Data publikacji:
2010-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.25.Jb
79.60.-i
Opis:
The X-ray electron photoemission spectra of a $Tl_{0.7}Bi_{0.3}Sr_{1.6}Ba_{0.4}CaCu_2O_{y}$ superconductor were measured with $Al K_{α}$ and $Mg K_{α}$ radiation at room temperature. The Bi 4f spectrum was compared to the same spectra of $Bi_{1.75}Pb_{0.35}Sr_{1.9}Ca_{2.05}Cu_{3.05}O_{y}$ and $Tl_{0.6}Pb_{0.4}Sr_{1.6}Ba_{0.4}Ca_2Cu_3O_{y}$ superconductors. In Bi,Pb-based superconductor only one type of $Bi^{3+}$ ions is present. The Bi 4f spectrum in the Tl,Bi-superconductor consists of two contributions due to the different valences. The component from $Bi^{5+}$ lines is in higher binding energy than from $Bi^{3+}$. The ratio of trivalent $Bi^{3+}$ to pentavalent $Bi^{5+}$ bismuth ions was calculated from decomposition of the spin-orbit split spectrum of the Bi 4f photoelectrons. The conclusion is that Bi is present in trivalent and in pentavalent form and the ratio of $Bi^{3+}$ to $Bi^{5+}$ is 1.87 ± 0.02.
Źródło:
Acta Physica Polonica A; 2010, 118, 2; 393-395
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Band Structure and Photoemission States of $Bi_{1.96}Mg_{0.04}Se_3$
Autorzy:
Tokarz, W.
Zalecki, R.
Kowalik, M.
Kołodziejczyk, A.
Kozłowski, A.
Miotkowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1374118.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.-b
71.55.Ak
72.80.Ga
75.47.Lx
79.60.-i
Opis:
We present theoretical band structure calculations and ultraviolet electron photoemission spectroscopy of a topological insulator $Bi_{1.96}Mg_{0.04}Se_3$. Our calculations were based on the first-principles density functional theory with general gradient approximation using Wien2k package with the spin-orbit interaction included by a second-variation method. The R3̅m crystal structure was optimized. In consequence, 4% decrease of volume and 3% decrease of ratio c/a was obtained. This modified structure was multiplied three times in a and b direction in order to place proper amount of Mg. Final crystal structure P3m1 with 135 atoms was used for the calculations. As a result metallic band structure was obtained with conduction band extended from -5.6 eV up to 0.16 eV. It composes mostly from Se p states. Comparison of total DOS with ultraviolet photoemission spectrum shows similar features.
Źródło:
Acta Physica Polonica A; 2014, 126, 4a; A-127-A-129
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetoresistance study of c-axis oriented YBCO thin film
Autorzy:
Chrobak, M.
Woch, W.
Kowalik, M.
Zalecki, R.
Giebułtowski, M.
Przewoźnik, J.
Kapusta, Cz.
Szwachta, G.
Powiązania:
https://bibliotekanauki.pl/articles/1054863.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
74.78.-w
74.25.Op
74.25.Qt
74.78.Bz
Opis:
The c-axis orientation YBa₂Cu₃O_δ thin film was prepared directly on MgO substrate by the pulse laser deposition. The thickness of the film is 170 nm. The superconducting critical temperature is T_{c50%}=87.5 K and the width of superconducting transition is ΔT = 1.8 K. The temperature dependences of magnetoresistance were measured up to 90 kOe. The widths of the transition to the superconducting state versus applied magnetic field were derived and they were fitted using the formula: Δ T=CH^m +Δ T₀. The irreversibility fields as a function of temperature were obtained and fitted by the de Almeida and Thouless-like equation: H_{irr}=H_{irr0}(1-T/T_{c0})^n. The irreversibility field at the liquid nitrogen temperature was calculated and it is H_{irr}=43.8 kOe when the applied magnetic field is parallel to the c-axis.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1018-1020
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
MnAs Overlayer on GaN(000$\text{}_{1}$)-(1 x 1) - Its Growth, Morphology and Electronic Structure
Autorzy:
Kowalski, B. J.
Kowalik, I. A.
Iwanowski, R. J.
Łusakowska, E.
Sawicki, M.
Sadowski, J.
Grzegory, I.
Porowski, S.
Powiązania:
https://bibliotekanauki.pl/articles/2038151.pdf
Data publikacji:
2004-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.55.-a
73.20.At
Opis:
MnAs layer has been grown by means of MBE on the GaN(000$\text{}_{1}$)-(1 x 1) surface. Spontaneous formation of MnAs grains with a diameter of 30-60 nm (as observed by atomic force microscopy) occurred for the layer thickness bigger than 7 ML. Ferromagnetic properties of the layer with Curie temperature higher than 330 K were detected by SQUID measurements. Electronic structure of the system was investigated in situ by resonant photoemission spectroscopy for MnAs layer thickness of 1, 2, and 8 ML. Density of the valence band states of MnAs and its changes due to the increase in the layer thickness were revealed.
Źródło:
Acta Physica Polonica A; 2004, 105, 6; 645-650
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photoemission Study of Mn 3d Electrons in the Valence Band of Mn/GeMnTe
Autorzy:
Pietrzyk, M. A.
Kowalski, B. J.
Orłowski, B. A.
Knoff, W.
Osinniy, V.
Kowalik, I. A.
Story, T.
Johnson, R. L.
Powiązania:
https://bibliotekanauki.pl/articles/2047678.pdf
Data publikacji:
2007-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.60.-i
71.20.Mq
Opis:
We present the results of the electronic band structure study of Ge$\text{}_{0.9}$Mn$\text{}_{0.1}$Te epilayers, clean and modified in situ by deposition of manganese atoms. The sets of resonant photoemission spectra were measured for the photon energy range covering the energy of Mn 3p→3d transition (45
Źródło:
Acta Physica Polonica A; 2007, 112, 2; 275-281
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
ZnCoO Films by Atomic Layer Deposition - Influence of a Growth Temperature οn Uniformity of Cobalt Distribution
Autorzy:
Łukasiewicz, M.
Witkowski, B.
Godlewski, M.
Guziewicz, E.
Sawicki, M.
Paszkowicz, W.
Łusakowska, E.
Jakieła, R.
Krajewski, T.
Kowalik, I.
Kowalski, B.
Powiązania:
https://bibliotekanauki.pl/articles/1791350.pdf
Data publikacji:
2009-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.55.Ln
68.55.Nq
78.66.Hf
81.15.Kk
Opis:
We report on the structural, electrical and magnetic properties of ZnCoO thin films grown by atomic layer deposition method using reactive organic precursors of zinc and cobalt. As a zinc precursor we applied either dimethylzinc or diethylzinc and cobalt(II) acetyloacetonate as a cobalt precursor. The use of these precursors allowed us the significant reduction of a growth temperature to 300°C and below, which proved to be very important for the growth of uniform films of ZnCoO. Structural, electrical and magnetic properties of the obtained ZnCoO layers will be discussed based on the results of secondary ion mass spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, atomic force microscopy, Hall effect and SQUID investigations.
Źródło:
Acta Physica Polonica A; 2009, 116, 5; 921-923
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fano Resonance of Eu$\text{}^{2+}$ and Eu$\text{}^{3+}$ in (Eu,Gd)Te MBE Layers
Autorzy:
Orlowski, B. A.
Kowalski, B. J.
Dziawa, P.
Pietrzyk, M.
Mickievicius, S.
Osinniy, V.
Taliashvili, B.
Kowalik, I. A.
Story, T.
Johnson, R. L.
Powiązania:
https://bibliotekanauki.pl/articles/2044511.pdf
Data publikacji:
2005-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.60.-i
71.20.Mq
Opis:
Resonant photoemission spectroscopy, with application of synchrotron radiation, was used to study the valence band electronic structure of clean surface of (EuGd)Te layers. Fano-type resonant photoemission spectra corresponding to the Eu 4d-4f transition were measured to determine the contribution of 4f electrons of Eu$\text{}^{2+}$ and Eu$\text{}^{3+}$ ions to the valence band. The resonant and antiresonant photon energies of Eu$\text{}^{2+}$ ions were found as equal to 141 V and 132 eV, respectively and for Eu$\text{}^{3+}$ ions were found as equal to 146 eV and 132 eV, respectively. Contribution of Eu$\text{}^{2+}$4f electrons was found at the valence band edge while for Eu$\text{}^{3+}$ it was located in the region between 3.5 eV and 8.5 eV below the valence band edge.
Źródło:
Acta Physica Polonica A; 2005, 108, 5; 803-807
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Control of Photon Polarization in GaAs/AlAs Single Quantum Dot Emission
Autorzy:
Suffczyński, J.
Trajnerowicz, A.
Kazimierczuk, T.
Piętka, B.
Kowalik, K.
Kossacki, P.
Golnik, A.
Nawrocki, M.
Gaj, J. A.
Wysmołek, A.
Stępniewski, R.
Potemski, M.
Thierry-Mieg, V.
Powiązania:
https://bibliotekanauki.pl/articles/2047725.pdf
Data publikacji:
2007-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Cr
78.66.Fd
78.67.Hc
78.47.+p
Opis:
We study polarization resolved correlation between photons emitted in cascaded biexciton-exciton recombination from a single quantum dot formed in type II GaAs/AlAs bilayer. Magnetic field induced transition from anisotropy controlled to the Zeeman controlled emission was demonstrated by a circular polarization correlation between the emitted photons. A simple model describing the effect allowed us to determine the anisotropic exchange splitting of the excitonic state. This method of the anisotropic exchange splitting determination can be useful in the case when other methods are not sensitive enough.
Źródło:
Acta Physica Polonica A; 2007, 112, 2; 461-466
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-10 z 10

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