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Tytuł:
The Electronic Structure and Specific Heat of $YNi_4Si$
Autorzy:
Pugaczowa-Michalska, M.
Falkowski, M.
Kowalczyk, A.
Timko, M.
Reiffers, M.
Mihalik, M.
Šebek, J.
Šantava, E.
Powiązania:
https://bibliotekanauki.pl/articles/1813671.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Be
71.20.-b
65.40.-b
Opis:
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.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 323-326
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Structure and Martensitic Transformation in Ni$\text{}_{2}$ MnGa Heusler Alloy
Autorzy:
Pugaczowa-Michalska, M.
Powiązania:
https://bibliotekanauki.pl/articles/2011090.pdf
Data publikacji:
1999-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.-b
Opis:
The electronic structure of the Ni$\text{}_{2}$MnGa Heusler alloy has been investigated for martensitic transformation β$\text{}_{1}$ → β'$\text{}_{1}$ → β"$\text{}_{1}$ → β'''$\text{}_{1}$ by the self-consistent TB-LMTO method. The distortion influences the shape of the densities of states. The β$\text{}_{1}$ is the most stable phase. We present the values of total and local magnetic moments for all phases of Ni$\text{}_{2}$MnGa alloy.
Źródło:
Acta Physica Polonica A; 1999, 96, 3-4; 467-473
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Structure and Magnetic Exchange Interaction in Fe₂NiAs Compound
Autorzy:
Wei, Xiao-Ping
Zhang, Ya-Ling
Sun, Xiao-Wei
Song, Ting
Zhu, Xing-Feng
Powiązania:
https://bibliotekanauki.pl/articles/1033418.pdf
Data publikacji:
2017-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Lp
71.20.Gj
71.20.-b
77.80.B-
Opis:
Using the spin-polarized relativistic Korringa-Kohn-Rostoker method, we study the electronic and magnetic properties of Fe₂NiAs compound with the Hg₂CuTi structure. Electronic calculations reveal the d-d orbital hybridization taking an important role in the compound. The calculated magnetic moments, which contain the spin and orbital moments, are primarily carried by Fe atoms located in A and B sites. The orbital moment of Fe₂NiAs system is rather small due to the cause of orbital quenching, implying a weak spin-orbit coupling. Simultaneously, we also study the influence of lattice constant on the magnetic moment, it is found that both spin and orbital moments are sensitive to the changes of lattice constants, i.e., the moments become larger as the expansion of lattice constant, indicating the enhancement of spin-orbit coupling effect. In addition, we investigate the magnetic interactions between the constituents to obtain the Heisenberg exchange coupling parameters. It is noted that the interactions are dominated by a strong exchange between Fe atoms. Finally, we acquire the Curie temperatures of Fe₂NiAs compound under different lattice constants by using mean field approximation.
Źródło:
Acta Physica Polonica A; 2017, 132, 4; 1320-1324
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
XPS Investigation of $Y_{1-x}Dy_xNi_2B_2C$ Superconductors
Autorzy:
Winiarski, A.
Winiarska, A.
Drzazga, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1812333.pdf
Data publikacji:
2008-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.-b
74.25.Jb
74.70.-b
82.80.Pv
Opis:
The analysis of the valence band photoemission spectra of $Y_{1-x}Dy_xNi_2B_2C$ (0≤x≤1) is presented. The valence bands are mainly plotted for Ni 3d, Y 4d and Dy 4f contributions, according to theoretical predictions. The valence bands of $Y_{1-x}Dy_xNi_2B_2C$ compounds markedly change shape with the x parameter, especially in the binding energy region from 3 eV to 14 eV. For large content of Dy (above 55%) the valence band is predominant by Dy 4f states whereas Ni 3d states govern the valence band of yttrium rich compounds. Changing in domination of valence sub-band correlates with plot of superconducting transition temperature $T_c$ with Dy concentration.
Źródło:
Acta Physica Polonica A; 2008, 114, 1; 243-246
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Structure and Magnetic Properties of Intermetallic Alloys
Autorzy:
Jezierski, A.
Pugacheva, M.
Morkowski, J. A.
Szajek, A.
Powiązania:
https://bibliotekanauki.pl/articles/1953169.pdf
Data publikacji:
1997-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.-b
75.10.Lp
Opis:
We present the influence of local ordering on the electronic and magnetic properties of Heusler-type alloys. The band structure and magnetic moments are calculated by ab initio spin-polarized tight binding linear muffin-tin orbital method. The calculated electronic density of states for Pd$\text{}_{2}$TiAl alloy is similar to ultraviolet photoelectron spectroscopy measurements. The self-consistent band calculations showed that the density of states at the Fermi level in Ni$\text{}_{2}$(Nb$\text{}_{(1-x)}$Ti$\text{}_{x}$)Sn and Ni$\text{}_{2}$(Nb$\text{}_{(1-x)}$Ta$\text{}_{x}$)Sn alloys decreased with the increase in Ti or Ta concentration. The total and local magnetic moments in ordered Rh$\text{}_{2}$TMSn (TM = Mn, Fe, Co, Ni, Cu) and Rh$\text{}_{2}$MnX (X = Al, Ga, In, Ge, Sb, Pb) Heusler-type alloys are calculated. The difference between theoretical and experimental results can be connected to the partial disorder in the samples.
Źródło:
Acta Physica Polonica A; 1997, 91, 1; 151-159
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ellipsometric Studies of NdMnO$\text{}_{3}$ Single Crystals
Autorzy:
Babonas, G. J.
Reza, A.
Szymczak, R.
Baran, M.
Shiryaev, S.
Fink-Finowicki, J.
Szymczak, H.
Powiązania:
https://bibliotekanauki.pl/articles/2037130.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.-b
78.20.Ci
Opis:
Ellipsometric studies of NdMnO$\text{}_{3}$ single crystals of orthorhombic symmetry were carried out in the spectral range 0.5-5.0 eV. Experimental data, which were obtained on the (001)$\text{}_{pc}$-type planes of pseudo-cubic system, were analyzed in the model of biaxial crystal. For the first time, three componentsε$\text{}_{x}$,ε$\text{}_{y}$,ε$\text{}_{z}$ of the effective dielectric function for manganites of orthorhombic symmetry were determined. From ellipsometric data, the spectra of optical conductivity and loss function were also calculated and considered. The fine structure of the spectra and optical anisotropy was the basis for discussion of the microscopic origin of the optical transitions responsible for the optical features. The electronic excitations due to dipole-forbidden spin-allowed transitions of the d-d-type in Mn-ions, f-f-type in Nd-ions and charge-transfer 2p(O)-3d(Mn) transitions were taken into account. The data for NdMnO$\text{}_{3}$ were compared with those obtained for other related undoped and doped single crystals of perovskite-type structure, LaMnO$\text{}_{3}$, (LaBa)(MnCo)O$\text{}_{3}$ and (LaCa)CoO$\text{}_{3}$.
Źródło:
Acta Physica Polonica A; 2004, 105, 1-2; 197-208
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Methods of Extracting Electron-Positron Enhancement Factors from Experimental ACAR Data
Autorzy:
Kontrym-Sznajd, G.
Rubaszek, A.
Powiązania:
https://bibliotekanauki.pl/articles/1929100.pdf
Data publikacji:
1993-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
71.20.-b
Opis:
Methods of extracting the full shape of the electron-positron momentum density from experimental angular correlation of positron annihilation radiation curves are discussed. The proposed analysis of experimental data allows more reliable verification of the form of electron-positron enhancement factors near the Fermi surface in simple metals.
Źródło:
Acta Physica Polonica A; 1993, 83, 3; 339-344
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Consistency and Symmetry Conditions for Line Projections
Autorzy:
Kontrym-Sznajd, G.
Jura, A.
Powiązania:
https://bibliotekanauki.pl/articles/2008102.pdf
Data publikacji:
1999-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.-b
78.70.Bj
Opis:
We present some relations between experimental spectra representing line projections of electronic densities in the momentum space. All spectra which are the projections of the same density, must be interdependent. It can be derived from the consistency condition and symmetry of the line projections. The knowledge of these dependences, found in the paper, can be utilised for an improvement of experimental data as e.g. two-dimensional angular correlation of positron annihilation spectra.
Źródło:
Acta Physica Polonica A; 1999, 95, 4; 586-590
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reconstruction of Densities from Compton Profiles with Applying Jacobi Polynomials
Autorzy:
Kontrym-Sznajd, G.
Samsel, M.
West, R. N.
Powiązania:
https://bibliotekanauki.pl/articles/2008105.pdf
Data publikacji:
1999-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.-b
78.70.Bj
Opis:
The advent of synchrotron sources has led to an increasing availability of high resolution Compton profiles J(p$\text{}_{z}$) and a consequent renewed interest in the reconstruction of the corresponding full momentum densities ρ(p). We present results of applying a new method in which the radial parts of ρ(p) and the measured profiles are expressed in terms of the Jacobi polynomials. The technique is demonstrated using model projections that correspond to Mg and Gd spectra. Reconstructed densities, being in very good agreement with model ones, are a very good performance of our new reconstruction algorithm.
Źródło:
Acta Physica Polonica A; 1999, 95, 4; 591-595
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Electronic and Magnetic Properties οf $Yb_xGd_{1-x}Ni_5$ Systems
Autorzy:
Szajek, A.
Werwiński, M.
Chełkowska, G.
Bajorek, A.
Chrobak, A.
Powiązania:
https://bibliotekanauki.pl/articles/1534374.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.-b
75.25.-j
Opis:
The intermetallic compounds $Yb_{x}Gd_{1 - x}Ni_5$ crystallize in the hexagonal $CaCu_5$-type structure. Based on wide ranging SQUID-type magnetometer, it was shown that the saturation magnetization decreases with growing concentration of ytterbium. The opposite tendency was observed for the Sommerfeld coefficient obtained in the heat capacity measurements. These results are confirmed using ab initio band structure calculations.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 905-906
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Structure and Magnetic Properties of the $UPdAs_2$ Compound
Autorzy:
Werwiński, M.
Szajek, A.
Powiązania:
https://bibliotekanauki.pl/articles/1427434.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.-b
75.25.-j
Opis:
The electronic band structure of $UPdAs_2$ is calculated using full potential linearized augmented plane wave implemented in the WIEN2k code. Calculations were started with the exchange-correlation potential in the form proposed by Perdew, Burke and Ernzerhof (PBE). We additionally studied PBE+U approach with the Coulomb repulsion energies U applied to the uranium 5f orbital and varying from 0 to 4 eV. PBE+OP with orbital polarization term was one more tested approach. To reproduce magnetic sequence ++- a doubled in c axis supercell is built. Initial magnetic moments on inequivalent uranium atoms are assumed to be opposite. The antiferromagnetic ground state is confirmed by comparison of total energies calculated for various magnetic configurations. Results of PBE+U(1.0 eV)+J(0.5 eV) and PBE+OP approaches are in the best agreement with the neutron scattering measurements of magnetic moments. The calculated total magnetic moment on uranium atoms is predicted to be equal to 1.47 $μ_{B}$.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1148-1150
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Structure and Magnetic Properties of $Ce_5CuPb_3$ Based on Ab Initio Calculations
Autorzy:
Werwiński, M.
Szajek, A.
Leśniak, P.
Malinowski, W.
Stasiak, M.
Powiązania:
https://bibliotekanauki.pl/articles/1427552.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.-b
75.25.-j
Opis:
$Ce_5CuPb_3$ band structure has been calculated based on two ab initio methods: full potential-linearized augmented plane wave implemented in WIEN2k code and full-potential local-orbital minimum-basis in FPLO code. The calculations were performed with and without spin polarization. Starting from the generalized gradient approximation we additionally tested either an orbital polarization correction and the GGA+U approach with the Coulomb repulsion energies U varied from 0 to 6.7 eV within the Ce 4f electron shell. The calculations confirmed possible antiparallel alignment of the magnetic moments of the cerium atoms in the low temperature phase.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1182-1184
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Electronic and Magnetic Properties of UGe Compound
Autorzy:
Werwiński, M.
Szajek, A.
Powiązania:
https://bibliotekanauki.pl/articles/1534263.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.-b
75.25.-j
Opis:
The UGe system crystallizes in the orthorhombic ThIn-type structure. The uranium atoms occupy three crystallographic sites with interatomic U-U distances like below and above the Hill limit. The band structure has been calculated by using the density functional theory and generalized gradient approximation. Ab initio calculations were performed based on the full-potential local-orbital minimum-basis code. Calculations showed that all three types of uranium atoms are magnetically ordered with antiparallel alignment of the magnetic moments. For uranium atoms with an interatomic distance below the Hill limit magnetic moments are significantly reduced due to hybridization effects.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 886-887
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Topographic and Energetic Heterogeneity Studies of Oxidized Graphite Surface by Scanning Tunneling Microscopy/Spectroscopy and Photoelectron Spectroscopy
Autorzy:
Klusek, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1963284.pdf
Data publikacji:
1997-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.16.Ch
71.20.-b
Opis:
Scanning tunneling microscopy and spectroscopy and X-ray photoelectron spectroscopy are used to study oxidation effects of nitric acid on a highly-oriented pyrolytic graphite surface. Various etching times at constant temperature are applied in order to create local binding sites on the surface without creating deep defects. A single and paired chains structure, different from pure graphite at atomic scale, is shown by scanning tunneling microscopy. This can be explained by the presence of oxygenate groups on the surface, revealed by X-ray photoelectron spectroscopy. Both scanning tunneling spectroscopy and X-ray photoelectron spectroscopy demonstrate the vanishing of π bands characteristic of sp$\text{}^{2}$ graphite hybridization. This, in turn, can be explained by dehybridization related to new bondings of the graphite carbons in the oxygenate groups. An important result of area averaging spectroscopy is the observed energetic heterogeneity considered in terms of the changes of local electronic density of states of the oxidized surface.
Źródło:
Acta Physica Polonica A; 1997, 91, 3; 569-582
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
XPS Valence Band Studies of $LaNi_{5-x}Mₓ$ (M = Al, Co; x = 0, 1) Alloy Thin Films
Autorzy:
Skoryna, J.
Marczyńska, A.
Pacanowski, S.
Szajek, A.
Smardz, L.
Powiązania:
https://bibliotekanauki.pl/articles/1386422.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.-f
71.20.-b
Opis:
$LaNi_{5-x}Mₓ$ (M = Al, Co) alloy thin films were prepared onto oxidised Si(100) substrates in the temperature range of 285-700 K using UHV magnetron co-sputtering. The surface chemical composition and valence bands of all the alloy thin films were measured in situ, immediately after deposition, transferring the samples to an UHV analysis chamber equipped with X-ray photoelectron spectroscopy. Results showed that the shape of the valence bands measured for the polycrystalline samples is practically the same compared to those obtained theoretically from ab initio band structure calculations. On the other hand, the X-ray photoelectron spectroscopy valence bands of the nanocrystalline thin films (especially LaNi₄Co) are considerably broader compared to those measured for the polycrystalline samples. This is probably due to a strong deformation of the nanocrystals. Therefore, the different microstructure observed in polycrystalline and nanocrystalline alloy thin films leads to significant modifications of their electronic structure.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 430-432
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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