Autor: Varga, R. - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Angular dependence of magnetization reversal in microwire studied by MOKE
Autorzy:: Váhovský, O.
Varga, R.
Tematy:: 75.50.Kj
75.60.Ej; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1054831.pdf Link otwiera się w nowym oknie
Opis:: In this work we present magneto-optical Kerr effect study of magnetization processes in amorphous glass - coated microwire of composition Fe_{77.5}Si_{7.5}B_{15}. Unique results obtained from microwire were compared to results of similar measurements on polycrystalline ribbon Co_2FeSi. In both cases reversal of longitudinal and transversal component of surface magnetization was studied. There was just a small variation in total change of magnetization caused by change in the direction of magnetic field in case of square hysteresis loops measured on microwire. However, switching field was angularly dependent and the change was considerably high and well predictable. The last two facts make such microwires outstanding candidates for sensors of magnetic field direction or spatial orientation.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Asymmetric Magneto-Impedance in CoFeSiB Amorphous Microwire
Autorzy:: Kravčák, J.
Varga, R.
Tematy:: 75.30.Gw
75.50.Kj
75.60.Ej; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1507026.pdf Link otwiera się w nowym oknie
Opis:: The symmetric dependences of magneto-impedance on the applied longitudinal dc magnetic field were measured in an amorphous CoFeSiB microwire. Additional application of a circumferential dc bias magnetic field was used to achieve the asymmetric magneto-impedance in the microwire. The obtained results are theoretically interpreted taking into account the cylindrical core-shell magnetic structure and the helical anisotropy induced during the microwire preparation. The observed very steep linear magneto-impedance dependences crossing H = 0 are promising for technical applications of the CoFeSiB microwire as a sensor of low magnetic fields.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Imaging the Surface Domain Structure of Amorphous Glass-Coated Microwires by Bitter Colloid
Autorzy:: Richter, K.
Varga, R.
Thiaville, A.
Tematy:: 75.60.Ch
75.60.Jk; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1199821.pdf Link otwiera się w nowym oknie
Opis:: The fast domain wall dynamics of amorphous glass-coated microwires can be changed drastically by properly selected annealing temperature. Here, the effect of thermal annealing on the surface domain structure of microwires is examined. Imaging the surface domain structure by Bitter colloid revealed the periodic pattern in each studied sample. Thermal annealing of microwires results in the five times increase of the domain wall velocity, as compared to the as-cast state. Influence of the surface domain structure on the fast domain wall propagation in microwires is discussed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Influence of Thermal Treatment on Domain Wall Dynamics in Glass-Coated Microwires
Autorzy:: Richter, K.
Varga, R.
Zhukov, A.
Tematy:: 75.60.Ej
75.60.Jk; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1506966.pdf Link otwiera się w nowym oknie
Opis:: We have studied the effect of thermal treatment on amorphous glass-coated $Fe_{40}Si_{7.5}B_{15}$ microwires. This microwire is characterized by transverse domain wall regime only, with maximum domain wall velocity of about 1500 m/s. Annealing at 200°C slightly increases its transverse domain wall velocity, probably due to the reduction of mechanical stresses during the thermal annealing. Annealing at 300°C leads to drastical increase of domain wall mobility and domain wall velocity of the transverse domain wall up to 2500 m/s. Moreover, vortex regime appears in this case. Thanks to it, maximum domain wall velocity of around 5000 m/s was observed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Negative Mobility of Single Domain Wall in Magnetic Microwires
Autorzy:: Varga, R.
Richter, K.
Zhukov, A.
Tematy:: 75.60.Ej
75.60.Jk; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1506994.pdf Link otwiera się w nowym oknie
Opis:: Here, we present the domain wall dynamics in thin magnetic wires that exhibit even negative mobility regime. Such a regime is well below the Walker limit and is a result of structural relaxation. It disappears at high frequencies and it can be enhanced by application of mechanical stress. Moreover, the domain wall velocity was found to be almost field-independent at certain measuring conditions. Anyway, the domain wall velocity remains quite high (> 450 m/s) in this regime.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Complex Permeability After-Effect and Analysis of Power Losses in Ferromagnetic Co-Based Amorphous Alloy
Autorzy:: Kravčák, J.
Varga, R.
Vojtaník, P.
Tematy:: 75.40.Gb
75.60.Ch
75.60.Lr; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1813518.pdf Link otwiera się w nowym oknie
Opis:: Complex permeability $(μ=μ_1-iμ_2)$ after-effect of near-zero magnetostrictive CoFeCrSiB amorphous alloy was investigated in magnetic field H (t)= $H_0$ exp ( i 2π f t) after demagnetization. For frequencies f from 200 Hz to 2000 Hz and for the small amplitude H_0 < $H_{cr}$ we observed practically constant both real $μ_1$ and imaginary part $μ_2$ of permeability. A measured small decrease in the real part $μ_1$ and increase in the imaginary part $μ_2$ with frequency f were theoretically calculated for a quadratic form of a domain wall potential $E_S$ (x)=1/2α $x^2$. The calculated loss factortan δ = $μ_2 μ_1$, which is small at amplitude $H_0$ < $H_{cr}$, corresponds to power losses due to eddy currents induced around reversibly moving domain walls.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Single Domain Wall Propagation at Low Fields
Autorzy:: Kostyk, J.
Varga, R.
Vazquez, M.
Tematy:: 75.60.Ch
75.60.Ej
75.78.Fg; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1366478.pdf Link otwiera się w nowym oknie
Opis:: We have studied the domain wall propagation at low fields regime in thin glass-coated microwire of composition $Fe_{77.5}Si_{7.5}B_{15}$. It is shown, that power law describes domain wall dynamics at low fields. Such behaviour results from the interaction of the propagating domain wall with the defects present in the material. At high fields, the domain wall mobility becomes negative. This can be explained as a result of domain structure relaxation. The exponent q from power law, which determines the domain wall shape, has a value of 0.19 for both cases, without applied stress and with applied stress of 20 MPa. This means, that domain wall shape is flexible in both measurements.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Influence of Thermal Treatment on Frequency Dependence of the Switching Field in Amorphous and Nanocrystalline FeNiMoB Microwires
Autorzy:: Komova, E.
Varga, R.
Vazquez, M.
Tematy:: 75.50.Kj
75.60.Ej
75.50.Tt; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1507122.pdf Link otwiera się w nowym oknie
Opis:: Amorphous and nanocrystalline ferromagnetic glass-coated microwires show excellent magnetic properties that make them very suitable to be employed as sensing elements in devices for technical applications. New $Fe_{40}Ni_{38}Mo_4B_{18}$ alloy composition can be appropriate to prepare soft magnetic nanocrystalline microwires which exhibit magnetic bistability even in the nanocrystalline state. Stability of magnetic properties after different thermal treatments ($T_{a}$ = 250-425°C) and after nanocrystallization was confirmed by the switching field $H_{sw}$ measurements. The frequency dependence of the switching field was investigated. Two contributions to the domain wall switching mechanism were recognized: magnetoelastic one coming from the magnetoelastic interaction of the magnetic moments with the stresses and relaxation one coming from the structural relaxation of local defects at atomic scale. But, the relative role of both contributions has been shown to vary strongly in different stage of devitrification.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Temperature Dependence of Magnetization Process in Bistable Amorphous and Nanocrystalline FeCoMoB Microwires
Autorzy:: Klein, P.
Varga, R.
Vazquez, M.
Tematy:: 75.50.Kj
75.60.Ej
75.60.Jk; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1534024.pdf Link otwiera się w nowym oknie
Opis:: We have studied the effect of thermal treatment on the magnetic properties of amorphous and nanocrystalline $Fe_{40}Co_{38}Mo_4B_{18}$ microwires. The magnetization process was measured within the temperature interval from 80 to 425 K. Microwires shows complex temperature dependence of the switching field in amorphous state due to the presence of complex stress distribution induced during production. After nanocrystallization, the switching field depends linearly on the measuring temperature that makes such microwires ideal for sensing applications.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Temperature Dependence of the Switching Field in Nanocrystalline FeNiMoB Microwires
Autorzy:: Klein, P.
Varga, R.
Vazquez, M.
Tematy:: 75.50.Kj
75.60.Ej
75.60.Jk; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1366629.pdf Link otwiera się w nowym oknie
Opis:: We have studied temperature dependencies of the switching field in as-cast and nanocrystalline glass-coated $Fe_{40}Ni_{38}Mo_{4}B_{18}$ microwires. The switching field shows complex temperature dependence in the as-cast state reflecting the complex stress distribution induced during annealing. The temperature dependence of the switching field depends strongly on the stage of nanocrystallization being negative for low temperatures of annealing and positive for annealing at 700 K.
Dostawca treści:: Biblioteka Nauki

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