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1
Content available remote

Electronic Structure and Magnetic Properties of Ce_5CuPb_3 Based on Ab Initio Calculations

100%
Werwiński M., Szajek A., Leśniak P., Malinowski W., Stasiak M.
Acta Physica Polonica A
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2012
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vol. 121
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issue 5-6
1182-1184
EN
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.
2
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Magnetic Order in TbPdIn

100%
Javorský P., Fikáček J., Prokleška J., Nishigori S., McIntyre G.
Acta Physica Polonica A
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2010
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vol. 118
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issue 5
879-880
EN
The magnetic structure in TbPdIn was investigated by neutron diffraction experiments. The results reveal a long-range magnetic structure with propagation vector (0,0,0) and the Tb moments forming a non-collinear structure within the basal plane that is unchanged over the whole temperature region below the ordering temperature of 66 K.
3
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Electronic Structure and Magnetic Properties of the UPdAs_2 Compound

100%
Werwiński M., Szajek A.
Acta Physica Polonica A
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2012
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vol. 121
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issue 5-6
1148-1150
EN
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}.
4
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The Electronic and Magnetic Properties of UGe Compound

100%
Werwiński M., Szajek A.
Acta Physica Polonica A
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2010
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vol. 118
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issue 5
886-887
EN
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.
5
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The Electronic and Magnetic Properties οf Yb_xGd_{1-x}Ni_5 Systems

100%
Szajek A., Werwiński M., Chełkowska G., Bajorek A., Chrobak A.
Acta Physica Polonica A
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2010
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vol. 118
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issue 5
905-906
EN
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.
6
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Magnetic Structures of Ho_5Rh_4Ge_{10}

80%
Szytuła A., Penc B., Hofmann M., Sikora W.
Acta Physica Polonica A
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2013
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vol. 124
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issue 6
1002-1004
EN
A powder diffraction measurement of Ho_5Rh_4Ge_{10} is reported. This compound crystallizes in the tetragonal Sc_5Co_4Si_{10}-type structure (space group P4/mbm) in which the Ho atoms occupy three different sites. The neutron diffraction measurements indicate antiferromagnetic order with the Néel temperature T_{N}=7 K. Below T_{N} an additional phase transition at 4.5 K connected with the change of the magnetic structure is observed. The Ho moments in 4(h) site form collinear order up to T_{N} while moments at 2(a) site form sine modulated structure. Determined experimentally magnetic structures are compared to the results of symmetry analysis.
7
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Influence of Carbon on Spin Reorientation Processes in Er_{2-x}R_xFe_{14}C (R~=~Gd, Pr) - Mössbauer and Magnetometric Studies

80%
Pędziwiatr A., Krawiec K., Bogacz B., Kapusta C., Przewoźnik J., Kaczorowski D., Talik E.
Acta Physica Polonica A
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2011
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vol. 119
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issue 1
48-51
EN
The Er_{2-x}R_{x}Fe_{14}C (R=Gd, Pr) polycrystalline compounds have been synthesized and investigated with ^{57}Fe Mössbauer spectroscopy and magnetic measurements. The spin reorientation phenomena were studied extensively by narrow step temperature scanning in the neighborhood of the spin reorientation temperature. Obtained Mössbauer spectra were analyzed using a procedure of simultaneous fitting and the transmission integral approach. Consistent description of Mössbauer spectra were obtained, temperature and composition dependencies of hyperfine interaction parameters and subspectra contributions were derived from fits and the transition temperatures were determined for all the compounds studied. Initial magnetization versus temperature measurements (in zero and non-zero external field) for Er_{2-x}Gd_{x}Fe_{14}C compounds allowed to establish the temperature regions of reorientation, change of magnetization value during the transition process. The results obtained with different methods were analyzed and the spin arrangement diagrams were constructed. Data obtained for Er_{2-x}Gd_{x}Fe_{14}C were compared with those for Er_{2-x}Gd_{x}Fe_{14}B series.
8
Content available remote

Propagation of Spin Waves in Ferrite Films with Metasurface

80%
Vysotskii S., Dudko G., Sakharov V., Khivintsev Y., Filimonov Y., Novitskii N., Stognij A., Nikitov S.
Acta Physica Polonica A
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2018
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vol. 133
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issue 3
508-510
EN
Magnetostatic surface waves (MSSW) propagation in YIG films with "leaky" and "resonant" metasurfaces (MS) is studied. "Leaky" MS was fabricated by ion etching of the subwavelength periodic structure in YIG film surface while "resonant" MS was formed by placing the subwavelength periodic array of YIG stripes onto the plane YIG film. The effects of filtration and the dispersion properties of MSSW in such structures are discussed.
9
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Magnetic and Neutron Diffraction Studies of the Polycrystalline and Nanoparticle TbMnO_3

80%
Bażela W., Dul M., Dyakonov V., Gondek Ł., Hoser A., Hoffmann J., Penc B., Szytuła A., Kravchenko Z., Nosalev I., Zarzycki A.
Acta Physica Polonica A
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2012
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vol. 122
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issue 2
384-390
EN
This paper reports on investigations of magnetic properties, crystal and magnetic structures on TbMnO_3 prepared in various ways, namely, as conventional polycrystalline sample and two nano particle specimens (synthesized with a sol-gel method at temperatures of 800 and 850°C). The X-ray and neutron diffraction data confirm the orthorhombic crystal structure (space group Pbnm, No. 62) without noticeable differences of the lattice parameters for poly- and nanocompounds. For the polycrystalline sample, a subsequent ordering of the Mn and Tb sublattices with decreasing temperature was observed. Namely, the Mn sublattice exhibits a modulated magnetic structure with the propagation vector k = (0, k_{x}, 0) in between 41-5 K. Below T = 21 K, a change from a collinear (A_{y} mode) into non-collinear (A_{y}G_{z} mode) structure was evidenced. Further decreasing of temperature below 10 K results in magnetic ordering of the Tb sublattice (modulated G_{x}A_{y}F_{z} mode). For nanoparticle compounds, magnetic ordering in the Mn and Tb sublattices is described by propagation vector k = (0, k_{y}, 0), with k_{y} components higher than observed for polycrystalline sample. The magnetic ordering in the Mn sublattice is described by a collinear A_{y} mode down to 1.6 K where the Tb moment becomes ordered (G_{x}A_{y} mode). The observed broadening of the Bragg peaks connected to the Tb sublattice suggests the cluster-like character of its magnetic structure.
10
Content available remote

Magnetic Properties and Magnetic Structure of DyCoSi_2 Compound

80%
Duraj R., Penc B., Szytuła A.
Acta Physica Polonica A
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2014
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vol. 125
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issue 5
1176-1178
EN
The results of new magnetic dc and neutron diffraction measurements of DyCoSi_2 compound are presented. Below T_{N} equal to 10.9 K the Dy moments form collinear G-type structure with the moment parallel to the c-axis. The value of Dy-moment equal to 5.5(2) μ_{B} are smaller than free Dy^{3+} ion value (10.0 μ_{B}). These and the three-step magnetization process indicate the strong influence of the crystal electric field on the stability of the magnetic order. Increase of the values of the lattice parameters at 1.5 K in reference of these at 20 K indicate magnetostriction effect at low temperatures.
11
Content available remote

Solution and Refinement of Magnetic Structures with Jana2006

80%
Petříček V., Henriques M., Dušek M.
Acta Physica Polonica A
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2016
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vol. 130
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issue 4
848-851
EN
The program Jana2006 allows the solution and refinement of regular, twinned, modulated, and composite structures against different diffraction data sets. Recently a new option for solving and refining magnetic structures from powder and single crystal neutron diffraction data has been developed.
12
Content available remote

Neutron Diffraction Studies of Tb_2Ni_{2-x}In Intermetallic Compounds

80%
Szytuła A., Baran S., Hoser A., Kalychak Y. M., Penc B., Tyvanchuk Y.
Acta Physica Polonica A
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2013
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vol. 124
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issue 6
994-997
EN
The magnetic ordering of the Tb_2Ni_{1.78}In and Tb_2Ni_2In have been studied by neutron diffraction measurements. Tb_2Ni_{1.78}In with the tetragonal Mo_2FeB_2-type (space group P4/mbm, tP10) is antiferromagnet with the Néel temperature equal to 20 K. Below this temperature Tb moments form collinear magnetic structure commensurate with the crystal, described by the propagation vectors equal to (1/4, 1/4, 1/2). Magnetic moment equal to 7.60(6) μ_{B} is parallel to c-axis. The Tb_2Ni_2In in the orthorhombic Mn_2 lB_2-type (space group Cmmm, oC10) was detected as an impurity in the studied sample. It orders antiferromagnetically below ≈ 100 K with collinear moment arrangement described by the propagation vector (1/2, 1/2, 1/2). t 1.6 K μ_{Tb} = 6.33(14) μ_{B} and is parallel to the c-axis.
13
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Magnetism in UCo_{0.88}Ru_{0.12}Ge Studied by Polarized Neutrons

80%
Vališka M., Pospíšil J., Nénert G., Stunault A., Prokeš K., Sechovský V.
Acta Physica Polonica A
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2014
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vol. 126
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issue 1
330-331
EN
UCoGe is an archetype of coexisting weak itinerant 5f-electron ferromagnetism (T_{C}~3 K, μ_{s}=0.03μ_{B}/f.u.) and superconductivity (T_{SC}~ 0.6 K) at ambient pressure. The Ru substitution for Co leads to an initial sharp increase of the T_{C} up to the maximum of T_{C}=8.5 K for x=0.12, increase of spontaneous magnetic moment and suppression of superconductivity. We have grown the UCo_{0.88}Ru_{0.12}Ge single crystal and studied magnetization along the principal crystallographic axes. To see the microscopic background of these findings we performed a polarized neutron diffraction experiment on D3 diffractometer in ILL. We have found that the Co and U moments are parallel in UCo_{0.88}Ru_{0.12}Ge, in contrast to the antiparallel configuration in UCoGe. This is probably the reason of the spontaneous magnetization increase with Ru doping.
14
Content available remote

Neutron Diffraction Studies of Nanoparticle DyMnO_3 Compound

80%
Szytuła A., Penc B., Dyakonov V., Baran S., Hoser A.
Acta Physica Polonica A
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2014
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vol. 125
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issue 1
65-66
EN
The neutron powder diffraction (NPD) measurements of the nano-size DyMnO_3 manganite have been performed. The obtained results indicate that this compound crystallizes in the orthorhombic crystal structure described by the space group Pnma. The Mn and Dy moments order antiferromagnetically at different temperatures and form modulated magnetic structure described by the propagation vector k=(k_x, 0, 0) with the different values of k_x component for the Mn and Dy sublattices. The values of k_x component for Mn sublattice increase with decreasing of the temperature and are smaller that in bulk compound. The wide Bragg peaks related to the Dy sublattice suggest that the magnetic order in this sublattice has the cluster-like character.
15
Content available remote

Influence of 1% Addition of Nb and W on the Relaxation Process in Classical Fe-Based Amorphous Alloys

51%
Pietrusiewicz P., Błoch K., Nabiałek M., Walters S.
Acta Physica Polonica A
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2015
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vol. 127
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issue 2
397-399
EN
This paper features investigations into the influence of small additions of alloying elements on: structure, as well as the temporal and thermal stability of magnetic properties, and the disaccommodation effect, for the following amorphous alloys: Fe₆₁Co₁₀Y₈Me₁B₂₀ (where Me = Nb, W). The structure of the investigated samples has been confirmed by the Mössbauer spectroscopy. The obtained results indicate a strong correlation between the structure and the disaccommodation of the studied alloys. The Mössbauer studies reveal different configurations of atoms in the amorphous alloy samples, and the results indicate various potential barriers between orientations of atom pairs. For this reason, to describe the disaccommodation effect, the distribution of activation energy should be taken into account. The distribution of activation energy has been related to the distribution of relaxation times.
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