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1
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Modeling Thermal Expansion of Ni_{2}MnGe

100%
Pugaczowa-Michalska M.
Acta Physica Polonica A
|
2009
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vol. 115
|
issue 1
194-196
EN
The present study of Ni_{2}MnGe is focused on describing the thermal properties of the alloy in the framework of first-principles electronic structure calculations coupled with a Debye treatment of the vibrating lattice. The electronic structure of Ni_{2}MnGe has been studied using the full-potential nonorthogonal local-orbital minimum basis method. Two approximations for Grüneisen parameter γ, i.e. Slater's and Dugdale and MacDonald's expressions were assumed.
2
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Electronic Structure and Martensitic Transformation in Ni_{2} MnGa Heusler Alloy

100%
Pugaczowa-Michalska M.
|
|
vol. 96
|
issue 3-4
467-473
EN
The electronic structure of the Ni_{2}MnGa Heusler alloy has been investigated for martensitic transformation β_{1} → β'_{1} → β"_{1} → β'''_{1} by the self-consistent TB-LMTO method. The distortion influences the shape of the densities of states. The β_{1} is the most stable phase. We present the values of total and local magnetic moments for all phases of Ni_{2}MnGa alloy.
3
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Comparative Study of Compressibility of Ni_2MnX (X=In, Sn, Sb) Heusler Alloys

100%
Pugaczowa-Michalska M.
Acta Physica Polonica A
|
2008
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vol. 113
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issue 1
629-632
EN
The present study is focused on the compressibility of Ni_2MnX (X = In, Sn, Sb) Heusler alloys, which were investigated from the first principles. The study of the pressure effect on the magnetic properties of Ni_2MnX (X = In, Sn, Sb) predicted the decrease in the total magnetic moment from ambient pressure to pressure above 20 GPa.
4
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Effect of Co Substitution on Ni₂MnGe Heusler Alloy: ab initio Study

100%
Pugaczowa-Michalska M.
Acta Physica Polonica A
|
2018
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vol. 133
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issue 3
495-497
EN
Ab initio calculations shown that the Co substitution instead of Ni in Ni₂MnGe with the L2₁ crystallographic structure leads to a decrease of the lattice constant and an increase of the total magnetic moment of the Ni_{2-x}Co_{x}MnGe compounds. The Mn(B) has the largest local moment above 3 μ_{B} coupled parallel to moments on the Ni(A,C) and Co(A,C), which are found in the ranges of 0.19÷0.26 μ_{B} for Ni(A,C) and 1.03÷0.97 μ_{B} for Co(A,C) for studied range of x. Using the results stemming from the total energy calculations, the values of bulk modulus and its pressure derivatives are estimated according to the Murnaghan EOS.
5
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Effect of Small Pt Doping on the Electronic Structure of NiMnSb Half-Heusler Alloys

100%
Pugaczowa-Michalska M.
Acta Physica Polonica A
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2003
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vol. 103
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issue 4
393-402
EN
The effect of small Pt doping on the electronic and magnetic properties of NiMnSb compound were studied using the spin-polarised tight-binding linear muffin-tin orbital method. The electronic structure of half-Heusler alloys depends on the relative arrangement of the atoms in the unit cell, changing from half-metal to metal. The local ordering drastically influences the value of the band gap. The self-consistent band calculations were performed for the experimental lattice constant and for the lattice parameter estimated from the minimum of the total energy.
6
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Bonding Analysis of BiFeO₃ Substituted by Gd³⁺

64%
Pugaczowa-Michalska M., Kaczkowski J.
Acta Physica Polonica A
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2015
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vol. 127
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issue 2
362-364
EN
We present results of first-principles calculations for Bi₅GdFe₆O₁₈ compound in idealized the rhombohedral R3c structure for a variety of magnetic ordering. Within DFT+U approach it is found that the insulating ground state with the G-type antiferromagnetic arrangement of Fe sublattice gives a minimal total energy for BiFeO₃ substituted by magnetically active Gd³⁺. The Bi₅GdFe₆O₁₈ compound has nonzero total magnetic moment, which arises from antiparallel spin moments on Fe sites and reduced spin moment on Gd. Chemical bonding of the studied compound is analyzed using partial density of states, electron localization function and charge density distribution.
7
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Strained Tetragonal Bain Paths in Fe_{3}Pt Invar

64%
Pugaczowa-Michalska M., Lipiński S.
Acta Physica Polonica A
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2000
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vol. 97
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issue 5
749-752
EN
Employing the LMTO-ASA method we calculated the total energy variation of Fe_{3}Pt along the tetragonal distortion path connecting fcc and bcc structures for isotropic biaxial path and uniaxially strained path and compare the results with energies for the unstrained path.
8
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Volume Effect on the Magnetism of Fe_{3-x}Cr_{x}Al

51%
Go A., Pugaczowa-Michalska M., Dobrzyński L.
Acta Physica Polonica A
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2009
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vol. 115
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issue 1
191-193
EN
Magnetic properties of Fe_{3-x}Cr_{x}Al alloys depend strongly on the unit cell volume. Purpose of this work is to investigate the dependence of the total and local magnetic moments on the lattice constant using the self-consistent spin-polarised TB-LMTO method.
9
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Orthorhombic Phase of La_{0.5}Bi_{0.5}NiO₃ Studied by First Principles

51%
Kaczkowski J., Pugaczowa-Michalska M., Jezierski A.
Acta Physica Polonica A
|
2018
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vol. 133
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issue 3
408-410
EN
The aim of presented first principles study of La_{0.5}Bi_{0.5}NiO₃ is to investigate electronic structure of orthorhombic phase Pbnm. The calculations show that metallicity and magnetism of the system are strongly related with hybridization between Ni 3d and O 2p. To improve the quality of the electronic structure description of the system, especially the treatment of correlation for the Ni 3d, we employ GGA, LDA, and GGA+U, LDA+U. The LSDA results give good agreement with experiment. Thus, the screening effects originating from the hybridized Ni 3d and O 2p electrons are sufficiently strong that they reduce the electronic correlations in the La_{0.5}Bi_{0.5}NiO₃, making it a weakly correlated metal.
10
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Electronic Structure and X-Ray Photoelectron Spectra of YNi_4B Compound

51%
Pugaczowa-Michalska M., Chełkowska G., Kowalczyk A.
Acta Physica Polonica A
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2003
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vol. 104
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issue 5
487-494
EN
The electronic structure of the ternary YNi_4B compound, crystallizing in the hexagonal CeCo_4B structure (P6/ mmm space group), was studied by X-ray photoelectron spectroscopy and ab initio calculations. Core levels and the valence band were investigated. The X-ray photoelectron spectroscopy valence band is compared with that obtained from ab initio calculations. The valence band spectrum at the Fermi level exhibits the domination of the Ni(3d) states, which are hybridized with 4d states of Y and 2p states of B. The theoretical electronic specific heat coefficientγ derived from N(E_F) is about 11.33 mJ/(mol K^2) for experimental lattice parameters. The calculated bulk modulus is B_0=1.61632 Mbar.
11
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Electronic Structure and Magnetic Properties of Ni_2MnGa_{1-x}Ge_{x} and Disordered Ni_{2}MnSn Heusler Alloys

51%
Pugaczowa-Michalska M., Jezierski A., Dubowik J., Kaczkowski J.
Acta Physica Polonica A
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2009
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vol. 115
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issue 1
241-243
EN
In this work we present the influence of atomic disorder on the electronic and magnetic properties of Ni_{2}MnGa_{1-x}Ge_{x} and Ni_{2}MnSn Heusler alloys. Ab initio band calculations were performed for the experimental lattice parameters. We applied SPR-KKR-CPA methods in the local spin density approximation.
12
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Electronic Structure of BiFeO₃ in Different Crystal Phases

51%
Kaczkowski J., Pugaczowa-Michalska M., Jezierski A.
Acta Physica Polonica A
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2015
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vol. 127
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issue 2
266-268
EN
The electronic structure of different phases of BiFeO₃ were calculated by using density functional theory. The DFT+U and semilocal Tran-Blaha modified Becke-Johnson potential were used. DFT+U results are in good agreement with previous calculations. Our results have shown that in case of R3c, Pnma, Pn2₁a BiFeO₃ has G-antiferromagnetic ordering and C-antiferromagnetic in case of Cm space group. In all calculated structures BiFeO₃ is a semiconductor with the band gap: 2.26 eV (2.27 eV) for R3c, 1.91 eV (1.66 eV) for Pnma, 1.99 eV (2.18 eV) for Pn2₁a and 2.09 eV (2.55 eV) for Cm within DFT+U (Tran-Blaha modified Becke-Johnson).
13
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Interlayer Exchange Coupling and Proximity Effect in V-Fe Multilayers

45%
Marczyńska A., Synoradzki K., Pugaczowa-Michalska M., Toliński T., Smardz L.
Acta Physica Polonica A
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2018
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vol. 133
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issue 3
597-600
EN
We have studied interlayer exchange coupling (IEC) in (110) oriented V/Fe multilayers with ultrathin sublayers up to 7 monolayers (ML). Results showed that IEC energy depends on both vanadium and iron layer thicknesses. The local maxima of the antiferromagnetic coupling were found for V(7 ML)/Fe(4 ML) and V(3 ML)/Fe(3 ML) multilayers (MLs). The strongest AFM coupling energy of about 1.0 mJ/m² was measured at 5 K for the V(7 ML)/Fe(4 ML) multilayer. The position of the AFM peak for V(X ML)/Fe(3 ML) MLs near 3 ML of V spacer was also revealed by ab-initio calculations. Furthermore, theoretical calculations show an induced negative magnetic moment on V atoms near the V-Fe and Fe-V interfaces due to the proximity effect.
14
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Interlayer Exchange Coupling in Nb/Fe Multilayers

45%
Marczyńska A., Pugaczowa-Michalska M., Szymański B., Majchrzycki Ł., Smardz L.
Acta Physica Polonica A
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2018
|
vol. 133
|
issue 3
605-608
EN
The (110) oriented Nb-Fe multilayers (MLs) with constant Fe and variable Nb sublayer thicknesses were prepared at room temperature using UHV magnetron sputtering. The artificial periodicity was revealed by intense satellite peaks in the low- and high-angle X-ray diffraction patterns. Magnetic hysteresis loop measurements at 5 K revealed antiferromagnetic (AF) exchange coupling of the Fe sublayers for Nb spacer thickness of about 3 monolayers. The corresponding AF coupling energy is equal to about -1.36 mJ/m². The Nb spacer thickness corresponding to the position of the AF peak is in good agreement with ab-initio calculations within localized spin density approximations of exchange-correlation potential.
15
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Modification of Exchange Coupling in Fe/Nb/Fe/Pd Layered Structures using Hydrogen

39%
Wachowiak M., Marczyńska A., Dawczak-Dębicki H., Pugaczowa-Michalska M., Pacanowski S., Majchrzycki Ł., Smardz L.
Acta Physica Polonica A
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2018
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vol. 133
|
issue 3
609-612
EN
Fe/Nb/Fe trilayers were prepared at room temperature using UHV magnetron sputtering. The interlayer exchange coupling energy was determined from a shift of the minor hysteresis loop from the origin. Results showed clear antiferromagnetic (AF) coupling maxima near ım6 and 9 monolayers of Nb spacer. Calculations of the interlayer exchange coupling energy were carried out using ab-initio method with localized spin density approximations of exchange-correlation potential. The experimental results were in good agreement with ab-initio calculations. Furthermore, the position of the AF peaks and coupling energy values could be modified using hydrogen.
16
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The Electronic Structure and Specific Heat of YNi_4Si

33%
Pugaczowa-Michalska M., Falkowski M., Kowalczyk A., Timko M., Reiffers M., Mihalik M., Šebek J., Šantava E.
Acta Physica Polonica A
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2008
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vol. 113
|
issue 1
323-326
EN
The studies of the electronic structure and the specific heat of YNi_4Si are reported. Below the Fermi energy (E_F) the density of states contains mainly the 3d states of Ni, which hybridized with 4d states of Y and 3p states of Si. The theoretical electronic specific heat coefficient (12.32 mJ/(mol K^2)) obtained for equilibrium lattice parameters and the experimental value (13 mJ/(mol K^2)) are in a reasonable agreement.
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