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1
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Current-Induced Magnetic Dynamics in Asymmetric Ferromagnetic Single-Electron Devices

100%
Kowalik M.
Acta Physica Polonica A
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2009
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vol. 115
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issue 1
290-292
EN
The theoretical calculations of possible dynamics for a localized magnetic moment of the central electrode in ferromagnetic single-electron devices are presented. The spin-transfer torque from spin current absorbed by the central electrode is calculated. Thereafter, an in-plane component of spin torque is regarded during the integration of the Landau-Lifshitz-Gilbert equation and the time evolution of the localized magnetic moment of the central electrode is obtained. The necessary conditions for switching of the magnetic moment are discussed.
2
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The effect of PCB126, 77, and 153 on the intracellular mobilization of Ca+2 in bovine granulosa and luteal cells after FSH and LH surge in vitro

64%
Mlynarczuk J., Kowalik M.
Polish Journal of Veterinary Sciences
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2013
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issue 3
3
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Nuclear progesterone receptor isoforms and their functions in the female reproductive tract

51%
Rękawiecki R., Kowalik M., Kotwica J.
Polish Journal of Veterinary Sciences
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2011
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issue 1
4
Content available remote

Electronic Band Structure and Photoemission States of La_{2/3}Pb_{1/3}MnO_3

51%
Tokarz W., Kowalik M., Zalecki R., Kołodziejczyk A.
Acta Physica Polonica A
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2012
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vol. 121
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issue 5-6
1151-1153
EN
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.
5
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Electronic Band Structure of La_{2/3}Pb_{1/3}Mn_{2/3}Fe_{1/3}O_3

51%
Tokarz W., Kowalik M., Kołodziejczyk A.
Acta Physica Polonica A
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2012
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vol. 121
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issue 4
876-878
EN
We present theoretical studies of electric and magnetic properties in manganese perovskite La_{2/3}Pb_{1/3}Mn_{2/3}Fe_{1/3}O_3. The calculations were carried out by means of the first-principles density functional theory (DFT) with general gradient approximation GGA+U using Wien2K package. The P-3c1 crystal structure was chosen from the detailed X-ray diffraction data for the perovskite. For Mn and Fe d electrons exact exchange energy was utilized. Different orientation of magnetic moments on Mn and Fe atoms was considered. The computed density of states display band gap for both spin orientations in accord with our previous work, indicating that this compound should show an insulating ground state
6
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Electronic States of Collosal Magnetoresistive Manganites La_{0.67}Pb_{0.33}Mn_{1-x}Fe_{x}O_{3} from Photoemission Spectroscopy

51%
Kowalik M., Zalecki R., Kołodziejczyk A.
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issue 2
277-280
EN
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.
7
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Electronic Band Structures of La_{2/3}Pb_{1/3}Mn_{2/3}(Fe,Co,Ni)_{1/3}O_{3}

51%
Kowalik M., Tokarz W., Kołodziejczyk A.
Acta Physica Polonica A
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2015
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vol. 127
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issue 2
251-253
EN
We present calculations of the electronic band structures of La_{2/3}Pb_{1/3}Mn_{2/3}(Fe,Co,Ni)_{1/3}O_{3} colossal magneto-resistance manganites. The calculations are based on first-principles density functional theory with general gradient approximation GGA+U using WIEN2k package. The calculations show that electronic structures of these compounds consist mainly of Mn 3d, O 2p, and (Fe,Co,Ni) 3d states, which are hybridized over whole valence bands. Substitution Mn ion by Fe, Co, or Ni ions reduces the Mn and O contributions to the valence bands and weakens the double exchange interaction. The results are in good agreement with available experimental data.
8
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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

45%
Zalecki R., Woch W., Kowalik M., Kołodziejczyk A., Gritzner G.
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issue 2
393-395
EN
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.
9
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Electronic Band Structure and Photoemission States of Bi_{1.96}Mg_{0.04}Se_3

39%
Tokarz W., Zalecki R., Kowalik M., Kołodziejczyk A., Kozłowski A., Miotkowski J.
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vol. 126
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issue 4a
A-127-A-129
EN
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.
10
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Magnetoresistance Study of c-Axis Oriented YBCO Thin Film

33%
Chrobak M., Woch W., Kowalik M., Zalecki R., Giebułtowski M., Przewoźnik J., Kapusta C., Szwachta G.
Acta Physica Polonica A
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2017
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vol. 131
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issue 4
1018-1020
EN
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.
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