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1
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Quantum Model for Metal-Insulator Transition in Amorphous Gd_{x}Si_{1-x}

100%
Paja A., Ornat M.
Acta Physica Polonica A
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2013
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vol. 124
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issue 4
717-719
EN
The model for experimentally observed metal-insulator transition induced by magnetic field in amorphous Gd_{x}Si_{1 - x} is presented. The method of calculation is based on the previously created model for amorphous alloys now developed to include magnetic field effects. The model is based on the quantum "2 k_{F}" scattering model theory where the pseudopotentials are replaced by the scattering matrix operators and the Fermi energy is properly determined by the accurate values of the phase shifts. The results agree very well with experimental data.
2
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The Effect of Spin-Orbit Scattering on the Electrical Resistivity of Disordered Materials

100%
Spisak B., Paja A.
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vol. 96
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issue 6
751-758
EN
The spin-orbit scattering of charge carriers is considered as an additional contribution to the potential scattering. The expressions for the effective cross-section and the relaxation time for disordered media are calculated. The results for the Coulomb screened potential are presented and compared with available experimental data.
3
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The Effect of Hydrogenation on the Electrical Resistivity of Amorphous Alloys

100%
Ornat M., Paja A.
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vol. 126
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issue 6
1296-1298
EN
Theoretical investigations of the influence of hydrogen contents on the electrical resistivity of amorphous metallic alloys have been carried out. We have made use of our method of calculations of the electrical resistivity of disordered systems based on the ground of Morgan-Howson-Saub and Evans models. Our method is fully quantum, includes multiple scattering effects and uses the scattering matrix operators for describing the electron-ion interactions. The model gives good agreement with experiment for many binary systems and should work for ternary systems as well, thus we performed calculations with hydrogen as one of the components of a ternary alloy. The results of our calculations show that the resistivity should increase with hydrogen concentration. Some experimental data confirm this predication.
4
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Size Effects on the Electrical Resistivity of the Ultra-Thin Metallic Film

100%
Paja A., Działo A.
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vol. 125
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issue 5
1220-1223
EN
In this article we investigate the electron-phonon interaction in metals in the system strongly reduced in one dimension. The Fermi sphere which represents the free-electron structure of a bulk metal was replaced by a discrete set of the Fermi disks. Using the variational expression for resistivity the temperature and film thickness dependences of the resistivity were derived and compared with experimental data.
5
Content available remote

Electron Transport and Spin Scattering in Very Thin Disordered Metallic Films

100%
Paja A., Spisak B.
Acta Physica Polonica A
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2007
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vol. 112
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issue 6
1289-1295
EN
We consider the electron transport through a very thin disordered metallic film doped with magnetic impurities. We treat the film as a quasi-two-Łinebreak -dimensional system with structural disorder where some ions have spins and other are spinless. The interaction of conduction electrons with localized spins is described by means of the exchange term of the Hamiltonian. The scattering is treated in the first Born approximation and the potential is assumed to be the Coulomb screened one. The total effective cross-section is calculated as a sum of the part responsible for the potential scattering and the second part which comes from the spin-spin scattering. The Fermi sphere splits into separate sheets due to the finite size of the system in the z direction, therefore, the cross-section and the relaxation time are calculated for each sheet independently. The total transport relaxation time and the conductivity are obtained as functions of the thickness of the system and the contents of magnetic impurities. Some model calculations have been made for a thin disordered film of copper doped with manganese.
6
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Content available

Transport Relaxation Time of Spin-Polarized Electrons

100%
Paja A., Spisak B.
Acta Physica Polonica A
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2004
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vol. 106
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issue 1
69-76
EN
We study the mechanism of spin relaxation in 3D disordered metallic systems due to the spin-orbit scattering on charged impurities. The transport relaxation time for spin-polarized conduction electrons is calculated analytically in the presented model, where the screened Coulomb potential is used for the description of impurities.
7
Content available remote

Electrical Resistivity of the Monoatomic Metallic Layer

100%
Paja A., Działo A.
Acta Physica Polonica A
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2013
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vol. 123
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issue 4
770-772
EN
We present new formula which describes the change of electrical resistivity of a monoatomic metallic layer with temperature. The results are compared with those given by the Bloch-Grüneisen formula for bulk metals. Our calculated values compared with those for bulk materials are significantly higher at low temperatures (T<0.1θ) and apparently lower at the remaining range of temperatures. Both effects can be explained by the low dimensionality of the sample.
8
Content available remote

Spin-Dependent Transport through Metallic System with Magnetic Impurities

81%
Spisak B., Wołoszyn M., Paja A.
Acta Physica Polonica A
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2009
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vol. 115
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issue 1
266-268
EN
The problem of spin-dependent transport of electrons through a metallic nanostructure is considered. The system consists of non-magnetic metal wire with two magnetic impurities and is connected to two ferromagnetic leads. The differential conductance is calculated by using the transfer matrix method. The spin polarization of the conductance is also obtained. It was found that this polarization is dependent on the spin configuration of magnetic impurities. This dependence can be controlled by the applied bias voltage.
9
Content available remote

Quasicritical Behaviour of the NMR and µSR Relaxation in YMn_{2}D_{x}

81%
Paja A., Mietniowski P., Figiel H.
Acta Physica Polonica A
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2000
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vol. 97
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issue 5
867-870
EN
The magnetic and structural properties of YMn_{2} are strongly influenced by introduction of hydrogen (deuterium) in the structure, however, it only slightly modifies the noncollinear antiferromagnetic structure of the compound. The temperature dependences of the NMR relaxation times T_{1} and T_{2} of deuterium and the zero-field relaxation of muons in YMn_{2}D_{x} were measured at temperatures above the magnetic ordering temperature T_{N}. The corresponding relaxation rates are described by the empirical expression (T/T_{N}-1)^{-η}, where the exponent η increases linearly with deuterium concentration x. To explain this behaviour, the Moriya theory of spin fluctuations was used. The expressions for NMR and μSR relaxation rates have been calculated. The resultant formulae agree well with the experiment, giving reasonable values of fitting parameters. The results obtained are discussed in terms of spin fluctuation excitation spectrum.
10
Content available remote

Temperature Dependence of Magnetisation Reversal and GMR in Spin Valve Structures

52%
Stobiecki F., Stobiecki T., Ocker B., Maass W., Powroznik W., Paja A., Loch C., Röll K.
Acta Physica Polonica A
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2000
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vol. 97
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issue 3
523-526
EN
Temperature measurements of magnetisation reversal, resistance and magnetoresistance of Co/Cu/Co/FeMn spin valve structures deposited in different conditions were performed. The influence of exchange anisotropy energy, interlayer coupling energy, and electron transport properties were taken into consideration in explaining differences in giant magnetoresistance effect of investigated samples.
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