Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 18

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

Search:
in the keywords:  75.47.De
help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1
Content available remote

Development of Giant Magnetoresistance Material Based on Cobalt Ferrite

100%
Djamal M., Ramli, Khairurrijal, Haryanto F.
Acta Physica Polonica A
|
2015
|
vol. 128
|
issue 2B
B-19-B-22
EN
This paper describes an experimental study on development of giant magnetoresistance material based on cobalt ferrite (CoFe₂O₄). We have successfully developed a new giant magnetoresistance material based on CoFe₂O₄ i.e; sandwich (CoFe₂O₄/CuO/CoFe₂O₄), spin valve (FeMn/CoFe₂O₄/CuO/CoFe₂O₄), and organic giant magnetoresistance (CoFe₂O₄/Alq₃/CoFe₂O₄) using dc-opposed target magnetron sputtering method. Crystalline structure and morphology of thin films were characterized by X-ray diffraction and scanning electron microscope. The electrical properties were characterized using a four-point probe and magnetic properties were characterized using a vibrating sample magnetometer. In sandwich structure, the giant magnetoresistance ratio maximum are found at room temperature in CoFe₂O₄/CuO/CoFe₂O₄ thin film is 70% when CoFe₂O₄ and CuO layer thickness are 62.5 nm and 14.4 nm, respectively. The maximum of giant magnetoresistance ratio of the spin valve structure obtained is 32.5% at FeMn layer thickness of 45 nm. Meanwhile, in organic giant magnetoresistance the maximum value of the giant magnetoresistance ratio are approximately 35.5% at room temperature.
2
Publication available in full text mode
Content available

Response of Grained La_{0.67}Ca_{0.33}MnO_3 Films to Microwave Radiation and the Method for Measuring Electrical Resistance of Grains

100%
Repšas K., Laurinavičius A., Vaškevičius R., Anisimovas F., Deksnys A., Vengalis B.
Acta Physica Polonica A
|
2006
|
vol. 110
|
issue 4
537-544
EN
It was found that the response of grained La_{0.67}Ca_{0.33}MnO_3 films to microwave radiation is of thermal nature. A nonresonant method for measuring of the electric resistance of grains was developed. It allows one to avoid the influence of the magnetic field of the wave on the measurement results. The measurements of the temperature dependences of the grain electric resistance indicate that in the vicinity of the maximum-resistance temperature T_m, the intrinsic electric resistance of the grains is more than by two orders of magnitude lower than the film resistance measured by applying the dc current. The obtained experimental results agree well with those given by resonant techniques.
3
Content available remote

Giant Magnetoresistance of [Ni_{80}Fe_{20}/Au/Co/Au]_{N} Multilayers Deposited on Flexible Substrates

100%
Gospodarczyk W., Urbaniak M., Stobiecki F., Szymański B.
Acta Physica Polonica A
|
2012
|
vol. 121
|
issue 5-6
1234-1236
EN
Magnetic hysteresis and magnetoresistance of [Ni_{80}Fe_{20}/Au/Co/Au]_{10} multilayers displaying giant magnetoresistance and sputtered on a flexible polypropylene substrates (an adhesive tape) is investigated. The magnetoresistive properties are very similar to those found in films prepared under the same conditions on Si(100) substrates. It is demonstrated, too, that a bendability of the substrates can be utilized to form cylindrically shaped magnetoresistive sensors with reduced anisotropy of the effect.
4
Content available remote

Changes of Structure and Magnetic Properties of (Ni_{80}Fe_{20}/Au/Co/Au)_N Multilayers as a Function of Repetition Number N

100%
Szymański B., Stobiecki F., Urbaniak M., Siffalovic P., Majkova E.
Acta Physica Polonica A
|
2008
|
vol. 113
|
issue 1
205-208
EN
The influence of repetition number N on magnetoresistance, magnetic reversal and structure of sputtered (Ni_{80}Fe_{20}/Au/Co/Au)_N multilayers was investigated. The multilayers are characterized by in-plane (Ni_{80}Fe_{20}) and out-of-plane (Co) magnetic anisotropy of ferromagnetic layers and show considerable magnetoresistance effect (ΔR/R) of the giant magnetoresistance type. Increased N results in an enhancement of ΔR/R from about 0.5% for N=1 up to above 5% for N=15. This enhancement is caused by: diminishing the role of electron scattering at the surfaces, decreasing the effect of structural imperfection and the lack of the perpendicular anisotropy of Co layer in the first period. The interpretation is corroborated by low ΔR/R value observed for N=1 and an evolution of the ΔR(H)/R dependence with increasing N. The anisotropy field of Co layers also increases with N.
5
Content available remote

Theoretical Studies of Tunnel Magnetoresistance and Shot Noise in a Schottky-Barrier Carbon Nanotube Transistor with Ferromagnetic Contacts

80%
Krompiewski S.
Acta Physica Polonica A
|
2008
|
vol. 113
|
issue 1
521-524
EN
A Schottky-barrier carbon nanotube field-effect transistor with ferromagnetic contacts was modelled. The theoretical method combines a tight-binding model and the non-equilibrium Green function technique. Tunnel magnetoresistance as well as current noise of the carbon nanotube field-effect transistor are the main issues addressed in this study. It is shown that the former may exceed 50%, whereas the latter is characterized by the Poissonian Fano factor (F) within the sub-threshold region, and the sub-Poissonian F≈0.5 for elevated gate voltages. Remarkably, reorientation of relative magnetization alignments of the contacts may lead to noticeable changes in the current noise.
6
Content available remote

Graphene Nanoribbons with End- and Side-Contacted Electrodes

80%
Krompiewski S.
Acta Physica Polonica A
|
2012
|
vol. 121
|
issue 5-6
1216-1218
EN
This contribution reports on theoretical studies of electronic transport through graphene nanoribbons in the two-terminal geometry. The method combines the Landauer-type formalism with Green's function technique within the framework of the standard tight-binding model. The aim of this study is to gain some insight on how fundamental electric current characteristics (conductance and shot noise) depend on interface conditions imposed by graphene nanoribbon/metal-electrode contact details. Calculations have been carried out for both end- and side-contact geometries, and metallic (zigzag-edge) as well as semiconducting (armchair-edge) graphene nanoribbons. It turns out that results for side-contacted systems depend on the ratio between the free-standing graphene nanoribbon length to that covered by the electrode. For sufficiently long nanoribbons the results start converging when this ratio exceeds 0.5. In the case of ferromagnetic contacts, the giant magnetoresistance coefficient is also discussed.
7
Content available remote

Comparative Studies on Giant Magnetoresistance in Carbon Nanotubes and Graphene Nanoribbons with Ferromagnetic Contacts

80%
Krompiewski S.
Acta Physica Polonica A
|
2009
|
vol. 115
|
issue 1
319-321
EN
This contribution reports on comparative studies on giant magnetoresistance in carbon nanotubes and graphene nanoribbons of similar aspect ratios (i.e. perimeter/length and width/length ratios, for the former and the latter, respectively). The problem is solved at zero temperature in the ballistic transport regime, by means of the Green functions technique within the tight-binding model and with the so-called wide band approximation for electrodes. The giant magnetoresistance effect in graphene is comparable to that of carbon nanotubes, it depends strongly on the chirality and only slightly on the aspect ratio. It turns out that graphene, analogously to carbon nanotubes may be quite an interesting material for spintronic applications.
8
Content available remote

Selective Modification of Magnetic Properties of Co_1 /Au/Co_2/Au Multilayers by He Ion Bombardment

80%
Urbaniak M., Stobiecki F., Engel D., Szymański B., Ehresmann A.
Acta Physica Polonica A
|
2009
|
vol. 115
|
issue 1
326-328
EN
We show that in a [Co_1/Au/Co_2/Au]_4 multilayer, where Co_{1(2)} denote Co layers of different thicknesses, a 10 keV He-ion bombardment with a 6×10^{14} ions cm^{-2} dose leads to changes of the easy direction from out-of-plane to in-plane in the thicker Co layers (t_{Co2} = 1 nm) while the perpendicular anisotropy of the thinner Co layers (t_{Co1} = 0.6 nm) is preserved. The investigated multilayers were obtained by sputtering and the thickness of the Au layers (t_{Au} = 4 nm) ensured that a direct coupling between the Co layers (through pinholes) and Ruderman-Kittel-Kasuya-Yosida-like interactions were negligible.
9
Content available remote

The Influence of He^+ Ion Bombardment on Magnetic Properties of NiFe/Au/Co/Au Multilayers

80%
Kuświk P., Szymański B., Urbaniak M., Stobiecki F., Sveklo I., Kisielewski J., Maziewski A., Jagielski J.
Acta Physica Polonica A
|
2009
|
vol. 115
|
issue 1
352-354
EN
The influence of He^+ ion bombardment on magnetoresistance, magnetization reversal and domain structure of sputtered (Ni_{80}Fe_{20}(2 nm)/Au(2 nm)/Co(0.6 nm)/Au(2 nm))_{10} multilayers was investigated. The samples were bombarded using He^+(30 keV) ions with fluences D varied from 10^{13} to 3×10^{16} He^+/cm^{2}. With increasing D the following changes in magnetic properties were observed: (i) exponential decay of the saturation field of Co layers, (ii) progressive decrease in magnetoresistance as a result of degradation of Co layers perpendicular anisotropy, (iii) linear decrease in stripe domain period with log(D).
10
Content available remote

Electrodeposition and Characterization of Co/Cu Multilayers

80%
Haciismailoglu M., Alper M., Kockar H., Karaagac O.
Acta Physica Polonica A
|
2016
|
vol. 129
|
issue 4
773-775
EN
Co/Cu multilayers having different bilayer number (total thickness) were electrodeposited on polycrystalline Cu substrates with a strong [100] texture from an electrolyte including Co and Cu ions under potentiostatic control. The structural data from X-ray diffraction (XRD) revealed that all films have face-centered cubic (fcc) structure, but their crystal textures change from [100] to [111] as the bilayer number increases. The magnetic analysis by vibrating sample magnetometer (VSM) showed that the magnetic moment per volume decreases as the bilayer number increases. Magnetoresistance (MR) measurements were made at room temperature in the magnetic fields of ± 12 kOe using the Van der Pauw (VDP) method with four probes. The samples with the bilayer number less than 111 exhibited giant magnetoresistance (GMR) with a negligible amount of anisotropic magnetoresistance (AMR), while the ones with the bilayer number larger than 111 have pure GMR effect.
11
Content available remote

Exchange Coupling in Magnetic Semiconductor Multilayers and Superlattices

80%
Furdyna J., Leiner J., Liu X., Dobrowolska M., Lee S., Chung J., Kirby B.
Acta Physica Polonica A
|
2012
|
vol. 121
|
issue 5-6
973-980
EN
The study of ferromagnetic semiconductors continues to be of great interest because of their potential for spintronic devices. While there has been much progress in our understanding of ferromagnetic semiconductor materials - particularly of the canonical III-V system Ga_{1-x}Mn_xAs - many issues still remain unresolved. One of these is the nature of interlayer exchange coupling in GaMnAs-based multilayers, an issue that is important from the point of view of possible spintronic applications. In this connection, it is important to establish under what conditions the interlayer exchange coupling between successive GaMnAs layers is antiferromagnetic or ferromagnetic, since manipulation of such interlayer exchange coupling can then be directly applied to achieve giant magnetoresistance and other devices based on this material. In this review we will describe magneto-transport, magnetization, and neutron reflectometry experiments applied to two types of GaMnAs-based multilayer structures - superlattices and tri-layers - consisting of GaMnAs layers separated by non-magnetic GaAs spacers. These measurements serve to identify conditions under which AFM coupling will occur in such GaMnAs/GaAs multilayer systems, thus providing us the information which can be used for manipulating magnetization (and thus also giant magnetoresistance) in structures based on the ferromagnetic semiconductor GaMnAs.
12
Content available remote

GMI Effect in Annealed Fe_{40}Ni_{38}Mo_{4}B_{18} Microwires

80%
Komova E., Šidik F., Klein P., Varga R., Vazquez M.
|
|
vol. 126
|
issue 1
74-75
EN
Amorphous glass-coated microwires are ideal material for miniaturized applications for sensing the temperature, stress and magnetic field. One of the key parameters for future applications is their time and thermal stability. It has been shown that stability can be improved by using nanocrystalline materials that combine good soft magnetic properties of amorphous matrix with high structural stability of crystalline grains. Such nanocrystalline materials are usually obtained by annealing of amorphous precursor. In the given contribution, the influence of dc current annealing on the domain structure and GMI effect in amorphous and nanocrystalline Fe_{40}Ni_{38}Mo_{4}B_{18} magnetic microwire has been studied. The annealing induces additional circular magnetic anisotropy, stress relief and structure homogenization. However, the increase of magnetostriction results in the decrease of GMI. Annealing at optimum crystallisation temperature results in an increase of the relative permeability due to the formation of the nanosized grains. Consequently, GMI amplitude is comparable to that of as-cast state.
13
Content available remote

Anisotropic Magnetoresistance of Ni Nanorod Arrays in Porous SiO₂/Si Templates Manufactured by Swift Heavy Ion-Induced Modification

80%
Fedotova J., Ivanou D., Mazanik A., Svito I., Streltsov E., Saad A., Zukowski P., Fedotov A., Bury P., Apel P.
Acta Physica Polonica A
|
2015
|
vol. 128
|
issue 5
894-896
EN
In this work anisotropic magnetoresistance in nanogranular Ni films and Ni nanorods on Si(100) wafer substrates was studied in wide ranges of temperature and magnetic field. To produce Ni films and nanorods we used electrochemical deposition of Ni clusters either directly on the Si substrate or into pores in SiO₂ layer on the Si substrate. To produce mesopores in SiO₂ layer, SiO₂/Si template was irradiated by a scanned beam of swift heavy 350 MeV ¹⁹⁷Au²⁶⁺ ions with a fluence of 5×10⁸ cm¯² and then chemically etched in diluted hydrofluoric acid. Pores, randomly distributed in the template have diameters of 100-250 nm and heights about 400-500 nm. Comparison of temperature dependences of resistance and magnetoresistance in Ni films and n-Si/SiO₂/Ni structures with Ni nanorods showed that they are strongly dependent on orientation of magnetic field and current vectors relative to each other and the plane of Si substrate. Moreover, magnetoresistance values in n-Si/SiO₂/Ni nanostructures can be controlled not only by electric field applied along Si substrate but also by additionally applied transversal bias voltage.
14
Content available remote

Complex Magnetoimpedance in Joule-Heated Co_{71,1}Fe_{3,9}Si_{10}B_{15} Microwires

80%
Komova E., Kozar J., Klein P., Varga R.
Acta Physica Polonica A
|
2017
|
vol. 131
|
issue 4
705-707
EN
Complex magnetoimpedance study is an alternating current technique that can be used to probe some properties of magnetic materials. We report on complex impedance measurements in low-negative magnetostrictive ferromagnetic CoFeSiB microwire. In these wires, the domain structure consists of two parts: an inner core, with domains oriented to the longitudinal direction of the wire, and an outer shell with circumferentially oriented domains. This magnetic structure is modified by AC current flowing through the microwire which produces an additional circumferential magnetic field H_Φpand significantly affects magnetic structure inside the wires. The additional circular magnetization process in wires was studied by impedance measurements as a function of the amplitude and the frequency of the AC current after gradual Joule heating. Changes in the magnetization processes are reflected in the real permeability values and loss factor values.
15
Content available remote

Spin Disordered Resistivity of the Heusler Ni₂MnGa-based Alloys

80%
Kamarád J., Kaštil J., Albertini F., Fabbrici S., Arnold Z.
Acta Physica Polonica A
|
2017
|
vol. 131
|
issue 4
1072-1074
EN
Electrical resistivity of the selected Heusler off-stoichiometric (NiCo)₂Mn(GaIn) alloys was studied in a wide range of temperature and magnetic field. A step-like change of resistivity (Δρ ≈24 μΩcm) was detected in the off-stoichiometric Ni_{1.85}Mn_{1.21}Ga_{0.94} alloy at temperature of martensitic structural transition. This Δρ is much more significant than one in the stoichiometric Ni₂MnGa alloy. In the case of the off-stoichiometric (NiCo)₂Mn(GaIn) alloys, an enormous change of resistivity, Δρ ≈ 200 μΩcm, accompanies the structural transition. Simultaneously, the maximum of the spin disordered resistivity ρ_{sd}(T) of austenite phase of the alloys is slightly dependent on composition of the alloy and vary from ≈30 μΩcm up to ≈45 μΩcm, in good agreement with theoretical calculations. Due to high sensitivity of the structural transition temperature of the alloys to magnetic field, the very pronounced magnetoresistance effects have been observed in the studied alloys.
16
Content available remote

Influence of the Deposition Temperature οn Magnetotransport Properties οf Ni-Fe/Au/Co/Au Multilayers

70%
Błaszyk M., Chomiuk P., Buchta K., Luciński T.
Acta Physica Polonica A
|
2009
|
vol. 115
|
issue 1
363-365
EN
A correlation between the growth process and electrical properties of [Ni_{80}Fe_{20}(2 nm)/Au(2 nm)/Co(0.8 nm)/Au(2 nm)]_{15} multilayers is presented. A set of multilayers of identical composition was deposited in different temperatures. The changes in giant magnetoresistance amplitude were correlated with the changes in Co layers growth process that occur in different temperatures. The in situ conductance measurement leads to the growth mechanism identification in high temperatures as formation of Co islands. Intensified islandisation of Co was eventually confirmed by the temperature changes in shape of the Hall voltage loops, and the evolution of Co layers contribution.
17
Publication available in full text mode
Content available

Layered Cobaltites: Synthesis, Oxygen Nonstoichiometry, Transport and Magnetic Properties

70%
Conder K., Podlesnyak A., Pomjakushina E., Stingaciu M.
Acta Physica Polonica A
|
2007
|
vol. 111
|
issue 1
7-14
EN
Complex cobalt oxide perovskite-derived compounds with a general formula LnBaCo_2O_{5+x} (Ln = rare earth) attracted considerable interests because of their interesting properties: magnetic and metal-insulator transitions, giant magnetoresistance, ionic conductivity, and a structural similarity to high temperature superconductors. All the compounds are oxygen non-stoichiometric (0
18
Content available remote

Hall Effect and Magnetoresistance in Magnetic Multilayers with Alternating In-Plane and Out-of-Plane Anisotropies

70%
Błaszyk M., Luciński T.
Acta Physica Polonica A
|
2008
|
vol. 113
|
issue 2
663-668
EN
A direct comparison between the Hall effects and giant magnetoresistance of ferromagnetic multilayers of similar composition (Ni_{80}Fe_{20}/Au/Co/Au)_N with alternating in-plane and out-of-plane magnetization direction of Co layers is presented. The characteristic features at magnetic field-dependence of giant magnetoresistance were correlated with the creation and annihilation of the stripe domains in Co layer, with perpendicular anisotropy. The nucleation field values were investigated as an Au layer thickness function. Furthermore, the in situ conductance measurement results characterised the island growth mode of the ferromagnetic layers. The percolation thicknesses were also indicated.
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.