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1
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Band Structure and Magnetic Properties of DO_{3}-Type Fe_{3-x}V_{x}Al Alloys. Super-Cell Approach

100%
Deniszczyk J., Borgieł W.
Acta Physica Polonica A
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2000
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vol. 98
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issue 5
551-554
EN
The electronic structure of Fe_{3-x}V_{x}Al alloys was calculated using the super-cell methodology of alloy modeling. The concentration range of x=0.0÷1.0 was investigated. For a concentration of x=0.0625 the energy based analysis reveals that vanadium prefers to replace the Fe atom at sites with the octahedral coordination. It was found that the iron atoms coordinated by the eight nearest-neighbor Fe atoms preserve their high magnetic moment up to a concentration of x=0.9375 even though the average total magnetic moment goes to zero. The relatively high (≃ -1.0μB) negative magnetic moment of V remains constant up to x≃ 0.5. In the concentration range of x=0.75÷0.9375 the gap at ε_{F} of the minority density of states is observed while the majority density of states displays a sharp peak structure at the Fermi energy. This feature suggests the heavy-fermion behavior of the Fe_{2}VAl compound.
2
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Electronic and Magnetic Properties of Y(FeV)_{12} Compound and its Carbides

100%
Deniszczyk J., Borgieł W.
Acta Physica Polonica A
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1997
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vol. 91
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issue 2
459-462
EN
Electronic and magnetic properties of body centered tetragonal YFe_{8}V_{4} carbon doped compounds were determined by tight-binding linear muffin-tin orbitals method assuming experimental values of lattice constants. Total, partial densities of states and magnetic moments for YFe_{8}V_{4} and its carbides for different positions of carbon within unit cell of parent compound were calculated and discussed. In spite of carbides' unit volume decrease enhancement of magnetization and Curie temperature were obtained. Results are in quantitative agreement with experimental data.
3
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Scalar Relativistic Spin Polarized Electronic Structure of Ferromagnetic fcc GdAl_{2}

100%
Borgieł W., Deniszczyk J.
Acta Physica Polonica A
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1993
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vol. 84
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issue 6
1071-1083
EN
One-particle electronic states of ferromagnetic single crystal Laves phase GdAl_{2} is calculated with the help of augmented spherical waves, based on density functional theory. Density of states, partial densities of states are presented. The behavior of the spectrum in the vicinity of the Fermi energy and the number of occupied states are discussed in detail.
4
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Electronic Structure and Electron-Transport Properties of (Gd_{1-x}Y_{x})_{2}In Compounds

100%
Borgieł W., Deniszczyk J.
Acta Physica Polonica A
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2000
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vol. 97
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issue 5
783-786
EN
Based on the electronic structure of the ferromagnetic Gd_{2}In and (Gd_{0.5} Y_{0.5})_{2}In compounds the high-temperature magnetic part of the electrical resistivity of (Gd_{1-x}Y_{x})_{2}In as a function of Y concentration was calculated and analyzed. The main interaction which causes the finite magnetic part of the conductivity was assumed in a form of stochastically distributed in space s-f interaction. The calculated resistivity of (Gd_{1-x}Y_{x})_{2}In alloys qualitatively reproduces the experimental data.
5
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Ab Initio Study of the ^{57}Fe Electric Field Gradient in (FeAl)_{1-x}T_x (T = 3d Element) Dilute Alloys with B2-Type Structure

81%
Michalecki T., Hanc A., Deniszczyk J., Borgieł W.
Acta Physica Polonica A
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2008
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vol. 114
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issue 6
1483-1491
EN
We present an ab initio study of the electric field gradient at Fe nuclei in the series of (FeAl)_{1-x}T_x dilute alloys with B2-type crystal structure. The ternary additions T, of concentration x ≈ 0.06, from the group of 3d-type transition metals (Ti, V, Cr, Mn, Co, Ni, Cu) are considered. Lattice, local valence electron (3d, 4p) and weakly bound 3p core electron contributions to electric field gradient are separated out and discussed in the context of the T-atom site preference and changes of the electronic structure upon alloying. Contrary to earlier reports, we found that for most Fe nuclei the dominant contribution comes from the d-type valence electrons cancelled partially by the 3p and 4p electric field gradients which are both of opposite sign to that of the 3d one. The shielding effect of 3p semicore electrons is found and related to the electric field gradient contributed by the local valence electrons.
6
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Resistivity of (Gd_{1-x}Y_{x})_{2}In Alloys at High Temperatures - Two-Band Model Approach

81%
Borgieł W., Deniszczyk J., Lipowczan M., Braun J.
Acta Physica Polonica A
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2000
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vol. 98
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issue 5
547-550
EN
Two-band model for the substitutionary binary alloy of different rare earth metals with relatively simple 4f multiplet structure placed within the transition metal host matrix was proposed and applied to (Gd_{1-x}Y_{x})_{2}In. The main interaction which causes the magnetic part of the resistivity was assumed in a form of stochastically distributed in space s-f interaction. The calculated high temperature spin disorder resistivity of (Gd_{1-x}Y_{x})_{2}In alloys reproduces well the experimental alloys data.
7
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Electrical Conductivity for the Strongly Correlated and Hybridized Hubbard Band

81%
Kosimow R., Borgieł W., Deniszczyk J.
Acta Physica Polonica A
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2000
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vol. 97
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issue 5
799-802
EN
The magnetic and electrical transport properties of strongly correlated Hubbard band (f-band) hybridizing with the non-correlated conduction band (c-band) was studied. The many-body model Hamiltonian was treated within the modified alloy analogy scheme and the resulting one-body problem was solved with the use of coherent potential approximation. Within the Kubo-Greenwood formalism the dc electrical conductivity for bcc magnetic system was calculated and its variation with temperature and number of electrons was examined for different values of the Coulomb and hybridization (V) coupling constants. We found that the effect of strong correlations and hybridization on the conductivity is similar to that produced by the scattering due to the s-f interaction (spin disorder resistivity).
8
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Anomalous Reversible Torque in Layered Superconducting Bi_{2}Sr_{2}CaCu_{2}O_{x} Single Crystal

81%
Drzazga Z., Borgieł W., Szymczak R., Szymczak H.
Acta Physica Polonica A
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1996
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vol. 89
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issue 1
91-98
EN
Magnetic anisotropy of layered superconducting Bi_{2}Sr_{2}CaCu_{2}O_{x} single crystal was investigated by the torque method in the reversible regime. The torque was analyzed in the model taking into account 2D layered structure. Considered model gives the better fit to the data when the magnetic field is applied near (a, b) plane. Obtained results establish to 6×10_{3} value of the superconducting effective mass anisotropy coefficient ε.
9
Content available remote

Magnetic and Electronic Properties of Disordered (Gd_{1 - x}Y_{x})_7Pd_3 Alloys - Theoretical Study

81%
Woźniakowski A., Deniszczyk J., Borgieł W.
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EN
The ab initio study of electronic and magnetic properties of (Gd_{1 - x}Y_{x})_7Pd_3 alloys are presented. The electronic structure calculations were performed using FP-LAPW method. Basing on the ground-state single-electron results the many particle s-f model for disordered alloy with strongly correlated band electrons was parameterized. The concentration dependence of the band structure, magnetic moment, and the Curie temperature is presented and discussed in reference to experimental data.
10
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Ab Initio Study of Electronic Structure and Magnetic Properties of Gd(Ni_{1-x}Fe_x)_3 Alloys

81%
Deniszczyk J., Woźniakowski A., Borgieł W.
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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.
11
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Elastic-Plastic Transition in MBE-Grown GaSb Semiconducting Crystal Examined by Nanoindentation

62%
Majtyka A., Trębala M., Tukiainen A., Chrobak D., Borgieł W., Räisänen J., Nowak R.
Acta Physica Polonica A
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2016
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vol. 130
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issue 4
1131-1133
EN
The present paper concerns the elastic-plastic nanodeformation of Te-doped GaSb crystals grown by molecular beam epitaxy on the n-type of GaSb substrate. The conventional analysis of nanoindentation data obtained with sharp triangular (Berkovich) and spherical tip revealed the elastic modulus (E=83.07± 1.78 GPa), hardness (H=5.19±0.25 GPa) and "true hardness" (H_{T}=5.73±0.04 GPa). The registered pop-in event which indicates the elastic-plastic transition in GaSb crystal points towards the corresponding yield strength (σ_{Y}=3.8±0.1 GPa). The origin of incipient plasticity in GaSb crystal is discussed in terms of elastic-plastic deformation energy concept.
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