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  1. 42 Acta Physica Polonica A

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  1. 7 Deniszczyk J.

  2. 6 Pugaczowa-Michalska M.

  3. 4 Dobrzyński L.

  4. 4 Jezierski A.

  5. 4 Szymański K.

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1
Content available remote

Volume Effect on the Magnetism of Fe_{3-x}Cr_{x}Al

100%
Go A., Pugaczowa-Michalska M., Dobrzyński L.
Acta Physica Polonica A
|
2009
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vol. 115
|
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.
2
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Ab Initio Study of Electronic and Magnetic Structure and Structural Phase Transition of (Fe_{1 - x}Mn_{x})_2P_{1 - y}Ge_{y} Alloys

63%
Deniszczyk J., Woźniakowski A., Kolano R., Kolano-Burian A.
Acta Physica Polonica A
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2012
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vol. 121
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issue 5-6
1162-1164
EN
The paper presents results of the ab initio electronic structure calculations performed for the (Fe_{0.5}Mn_{0.5})_2P_{0.67}Ge_{0.33} alloy, a member of (Fe_{1 - x}Mn_{x})_2P_{1 - y}Ge_{y} family of alloys showing a giant magnetocaloric effect. Calculations confirmed the strong relationship between the magnetic state and crystal structure of the alloy. To investigate the isostructural phase transition driven by external magnetic field observed in (Fe_{0.9}Mn_{1.1})P_{0.8}Ge_{0.2} we utilized the fixed spin moment approach. Total energy analysis confirmed the occurrence of isostructural phase transition.
3
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Ab Initio Study of Electronic Structure and Magnetic Properties of Gd(Ni_{1-x}Fe_x)_3 Alloys

63%
Deniszczyk J., Woźniakowski A., Borgieł W.
Acta Physica Polonica A
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2012
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vol. 121
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issue 5-6
1156-1158
EN
We present the ab initio investigations of the electronic and magnetic properties of magnetocaloric Gd(Ni_{1-x}Fe_x)_3 alloys. To simulate fractional concentrations the supercell approach was implemented and different configurations of iron atoms were considered. Energetical analysis of site preference and magnetic order was performed. The concentration dependence of the averaged total and local magnetic moments and of the valence band photoemission spectra are presented and discussed in reference to experimental data.
4
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Electronic Structure and Ordering Degree in Fe_3Al Alloy Doped with Transition Metals. Ab Initio Study

63%
Go A., Dobrzyński L.
Acta Physica Polonica A
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2012
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vol. 121
|
issue 5-6
1124-1127
EN
Fe_3Al alloy crystallizes in DO_3-type structure. In the perfectly ordered alloy there are two nonequivalent sublattices (A,C) and B, which are occupied by Fe atoms, whereas all D sites are taken by metalloid. Such perfect ordering is, however, difficult to achieve experimentally, and some disorder between B-D as well as (A,C)-D sublattices typically appears in real samples. This disorder modifies strongly electronic structure and magnetic properties. The aim of this contribution is to investigate total energy dependence of atomic exchange of sites between B-D and (A,C)-D positions in Fe_3Al as well as in alloys doped with transition metals using ab-initio technique. Furthermore, dependence of electronic and magnetic properties of Fe_3Al-based alloys on the crystallographic ordering is thoroughly investigated.
5
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Electronic Structure of Mg_2Ni_{1-x}Cu_{x}

63%
Jezierski A., Jurczyk M., Szajek A.
Acta Physica Polonica A
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2009
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vol. 115
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issue 1
223-225
EN
Nanocrystalline Mg_{2}Ni doped alloys are good materials for hydrogen storage. In this work we present the influence of the chemical disorder on the electronic structure of Mg_{2}Ni_{1-x}Cu_{x} alloys for 0 < x < 0.2. The electronic structure was calculated by ab initio full potential scalar relativistic local-orbital method in the coherent potential approximation. We observe the change of the density of states near the Fermi energy.
6
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Influence of Mn Doping on Magnetic and Structural Properties of Co₂FeSi Heusler Alloy

63%
Galdun L., Ryba T., Kováč J., Prida V., Hernando B., Vargová Z., Varga R.
Acta Physica Polonica A
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2017
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vol. 131
|
issue 4
866-868
EN
We have studied the effect of Mn doping on structural and magnetic properties of Co₂FeSi Heusler alloy. Co₂FeSi, Co₂Mn_{0.25}Fe_{0.75}Si and Co₂Mn_{0.5}Fe_{0.5}Si alloys were prepared by melt spinning technique which offers fast and simple production of large amount of materials in a single production step. The rapid quenching method provides an opportunity to prepare Heusler alloys with highly ordered L2₁ structure confirmed by X-ray analysis in all the samples. Magnetic measurements revealed high Curie temperatures (>1000 K) and well defined easy magnetization plane parallel with the ribbon plane. Those attributes predispose given samples for applications in spintronics.
7
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Effect of the Boron Addition on the Structure of the Ni-Mn-Co-In Alloys

63%
Prusik K., Matyja E., Zubko M., Kubisztal M., Chrobak A.
Acta Physica Polonica A
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2016
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vol. 130
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issue 4
1023-1025
EN
Series of Ni_{45.5-x}Co_{4.5}Mn_{36.6}In_{13.4}B_{x} (at.%, x=0, 0.05, 0.1, 0.5, 1.0) polycrystalline magnetic shape memory alloys produced by the induction melting were examined in terms of the structure and transition temperatures. The structure of the alloys was determined by the X-ray diffraction and transmission electron microscopy. Scanning electron microscopy and electron backscattering diffraction techniques were applied to obtain the microstructure and texture of alloys. Boron addition promotes nucleation of the second Co-rich and In-poor phase as well as causes decrease of the martensitic transformation temperatures.
8
Content available remote

Electronic Structure of Sm(Ni_{1-x}Co_{x})₃ Alloys - XPS and ab initio Study

63%
Majtyka A., Sikora M., Blachiński D., Chełkowska G., Deniszczyk J.
Acta Physica Polonica A
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2018
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vol. 133
|
issue 3
673-675
EN
The band structure investigations for Sm(Ni_{1-x}Co_{x})₃ alloys by means of X-ray photoelectron spectroscopy (XPS) and an ab initio density functional theory (DFT) calculations are presented. The aim was to determine an effect of Ni/Co substitution on the electronic structure of the alloys. Investigations have shown that the Ni/Co substitution results in a reconstruction of the valence band (VB), especially the intensity near the Fermi level decreases with Co content. An ab initio simulated XPS VB spectra agree qualitatively with experimental ones with the exception of the Sm-4f sub-spectra where the multiplet decomposition is observed. Calculations shown that variation of magnetization in Sm(Ni_{1-x}Co_{x})₃ is driven mainly by the Ni/Co-3d and Sm-5d states polarization and increases linearly with rising Co content.
9
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Effect of Alloying on Magnetism and Electronic Structure of Gd(In_{1-x}Snₓ)₃ System - ab initio Study

63%
Deniszczyk J., Bajorek A., Chełkowska G., Zipper E.
Acta Physica Polonica A
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2015
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vol. 127
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issue 2
427-429
EN
We present the results of ab initio study of electronic and magnetic properties of Gd(In_{1-x}Snₓ)₃ alloys carried out with the use of FP-LAPW method. Our precise ab initio calculations for the first time uniquelly confirmed experimentally based predictions that the ground state magnetic structure of the alloys is antiferromagnetic and that upon the In/Sn substitution the magnetic structure undergo transition, changing the antiferromagnetic ordering from the (π00)-type for the GdSn₃ compound to the (ππ0)-type for the GdIn₃ one. Moreover, calculations gave an explanation of the oscillatory variation of density of states at Fermi level indicated by XPS measurements.
10
Content available remote

Ni_2FeSi Heusler Glass Coated Microwires

63%
Galdun L., Ryba T., Prida V., Hernando B., Zhukova V., Zhukov A., Vargová Z., Varga R.
Acta Physica Polonica A
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2017
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vol. 131
|
issue 4
851-853
EN
We report on fabrication, structural and magnetic properties of novel Heusler-type glass coated Ni₂FeSi microwires that were prepared by the Taylor-Ulitovsky method, having a metallic nucleus diameter about 3.9 μm and total sample diameter of 39 μm. This single step and low cost fabrication technique offers to prepare up to km of glass-coated microwires starting from few g of cheap elements for diverse applications. The X-ray diffraction data from the metallic nucleus indicates L2₁ crystalline structure (a=5.563 Å), with a possible DO3 disorder. Magnetic measurements determined the Curie temperature well above the room temperature (770 K) together with uniform easy magnetization axis of the metallic core, which predisposes this material to a suitable candidate for spintronic applications.
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
|
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
Content available remote

The Electronic Structure and Specific Heat of YNi_4Si

51%
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.
13
Content available remote

Effect of Noncollinear Magnetic Order on the Hyperfine Interactions in Pt_{3}Fe

51%
Woźniakowski A., Deniszczyk J., Szymański K.
Acta Physica Polonica A
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2011
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vol. 119
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issue 1
65-67
EN
The investigations of the hyperfine interactions in Pt_{3}Fe with the noncollinear magnetic order by means of ab initio methods are presented. It is shown that the ground state magnetic order of Pt_{3}Fe is of noncollinear character. Electric field gradient and hyperfine magnetic field at ^{57}Fe nucleus were calculated and their dependence on the strength of Coulomb correlation interaction is discussed. The calculated values of electric field gradient correspond with the experimental data and the best agreement was found when the enhanced Coulomb correlation interaction for 3d-states of Fe was considered. Lattice, local valence electron (3d, 4p) and weakly bound 3p semicore electron contributions to electric field gradient are separated out and discussed.
14
Content available remote

Spectroscopic Properties of Cu Doped (80-x)Sb_2O_3-20Li_2O-xMoO_3 Glasses

51%
Petkova P., Touiri H., Soltani M.
Acta Physica Polonica A
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2013
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vol. 123
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issue 2
205-206
EN
The antimony oxide as part of the heavy metal oxide glasses is attractive to researchers in recent years. The new antimony oxide glasses have been successfully synthesized using silica crucible in the ternary system for undoped and doped (80-x)Sb_2O_3-20Li_2O-xMoO_3 (x = 20, 30 mol.%) doped with 0.1 mol.% CuO_2. The optical characterization in the visible spectral region has been carried out on the doped glasses. The role of the Jahn-Teller effect in Cu doped glasses is determined and the electron transitions in these cations have been determined.
15
Content available remote

Interplay of Crystal Structure Preference and Magnetic Ordering in High Entropy CrCoFeNiAl Alloys

51%
Jasiewicz K., Kaprzyk S., Tobola J.
Acta Physica Polonica A
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2018
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vol. 133
|
issue 3
511-513
EN
In this work, some relations between crystal structure and magnetic ordering in CrCoFeNiAl HEAs are discussed in view of the KKR-CPA calculations. Remarkably, it is noticed that the transition between fcc and bcc phases in the analysed CrCoFeNi_{x}Al and CrCoFeNiAl_{x} alloys is closely related to change in ordering of the local magnetic moments, namely the magnetic moment on Cr is either parallel (ferromagnetic) or antiparallel (ferrimagnetic) to the magnetic moments of other atoms (Co, Fe and Ni). On the whole, the theoretical diagram showing the fcc-bcc phase preference and their coexistence vs. alloy composition well corroborates with available experimental data.
16
Content available remote

Experimental Studies of S=1 Heisenberg Planar Antiferromagnetic Chain Ni(C_{11}H_{10}N_{2}O)_{2}Ni(CN)_{4}

51%
Čizmár E., Černák J., Orendáč M., Herrmannsdörfer T., Feher A.
Acta Physica Polonica A
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2000
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vol. 97
|
issue 3
579-582
EN
In this paper we discuss the results of experimental studies of specific heat and magnetic susceptibility of chain compound Ni(C_{11}H_{10}N_{2}O)_{2}Ni(CN)_{4}. We have observed a Schottky type anomaly at T=2.2 K in a temperature dependence of specific heat and the compound was identified as a S=1 Heisenberg antiferromagnetic chain with the subcritical exchange coupling D/k_{B}=5 K, D/|J|=5.2 and the strong in-plane anisotropy E/k_{B}=2.8 K. It has been found that the in-plane anisotropy affects the region of validity of a diluted exciton model [1] and a strong coupling model [2] for S=1 Heisenberg chains with the strong planar anisotropy. The analysis suggests that the in-plane anisotropy should be considered in any attempt to find a compound potentially located in the boundary of Haldane and "large-D" phases.
17
Content available remote

Effects of Core-Hole Screening on Spin-Polarised Auger Spectra from Ferromagnetic Ni

51%
Wegner T., Potthoff M., Nolting W.
Acta Physica Polonica A
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2000
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vol. 97
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issue 3
567-570
EN
We calculate the spin- and temperature-dependent local density of states for ferromagnetic Ni in the presence of a core hole at a distinguished site in the lattice. Correlations among the valence electrons and between valence and core electrons are described within a multi-band Hubbard model which is treated by means of second-order perturbation theory around the Hartree-Fock solution. The core-hole potential causes strong screening effects in the Ni valence band. The local magnetic moment is found to be decreased by a factor of 5-6. The consequences for the spin polarisation of CVV Auger electrons are discussed.
18
Content available remote

Comparative Study of Compressibility of Ni_2MnX (X=In, Sn, Sb) Heusler Alloys

51%
Pugaczowa-Michalska M.
Acta Physica Polonica A
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2008
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vol. 113
|
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.
19
Content available remote

First Principles Study of Stability and Electronic Structure οf TMH and TMH_2 (TM = Y, Zr, Nb)

51%
Kanagaprabha S., Asvinimeenaatci A., Sudhapriyanga G., JemmyCinthia A., Rajeswarapalanichamy R., Iyakutti K.
Acta Physica Polonica A
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2013
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vol. 123
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issue 1
126-131
EN
First principles calculations are performed by using Vienna ab initio simulation package within the framework of density functional theory to understand the electronic and structural properties of yttrium, zirconium and niobium hydrides. The equilibrium lattice constant, the bulk modulus, the total density of states and charge density distribution are analyzed in comparison with the available experimental and theoretical data. The X-ray diffraction pattern is also simulated to estimate the lattice constants of these hydrides. The formation energies are computed for rock-salt and fluorite structures using density functional theory. The calculated elastic constants obey the necessary stability conditions. A detailed analysis of the changes in density of states and electron density upon hydride formation has allowed us to understand the formation of these hydrides.
20
Content available remote

Analytical Description of SMA Actuator Dynamics based on Fermi-Dirac Function

51%
Kluszczyński K., Kciuk M.
Acta Physica Polonica A
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2017
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vol. 131
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issue 5
1274-1279
EN
The paper deals with possible application of the very promising SMART material - shape memory alloy. At the beginning the laboratory stand for investigation on dynamic behaviour of a SMA linear actuator is presented and results of measurements for the chosen SMA actuator F2000 are depicted and discussed. In the next stage the authors propose to use the so-called Fermi-Dirac function for description of SMA linear actuator dynamics. Applying this function for determining basic performance curve: shortening Δ L versus time t for different loads F requires proper modification of the Fermi-Dirac function and its conversion in the one-parameter family (with parameter F). Coefficients of this family are determined with the help of Hooke-Jeeves optimization algorithm and on the basis of experimental findings separately for activation and deactivation process. The both derived expressions were validated by additional laboratory investigations. Finally, the elaborated descriptions was employed in design procedure of a robot gripper. It was shown that the results of measurements for the gripper prototype are in satisfactory agreement with the results of calculations.
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