Dynamic scaling of magnetic hysteresis in micron-sized Ni80Fe20 disks

Lee, W. Y.; Choi, Byoung Kyu; Lee, J.; Yao, C.C.; Xu, Y. B.; Hasko, D. G.; Bland, J. A. C.

doi:10.1063/1.123632

Cited by 28 publications

(18 citation statements)

References 14 publications

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“…2͒ as predicted in theoretical work 1,2,4 and demonstrated experimentally. 9,10,13,14,17 The magnetizations of the NiFe and Co films are unable to respond immediately to the rapidly varying field and this effect becomes progressively more pronounced as the sweep rate increases. However, it is noticeable that there is a significant difference in the dynamic response to the sweep rate between the NiFe and Co films.…”

Section: Resultsmentioning

confidence: 99%

“…The search for a universal theory [1][2][3][4][5]8,18 ͑and its experimental verification 6,7,[9][10][11][12][13][14][15][16][17] ͒ of magnetic hysteresis in ultrathin films continues to be of central importance in magnetism. Over the past decade the dynamics of magnetization reversal has attracted significant attention as a test of universality hypotheses and scale-invariant descriptions of the energy loss per cycle ͑the hysteresis loop area͒ as a function of external parameters, e.g., applied magnetic field strength H 0 , frequency ⍀, and temperature T. Recent theoretical studies based on a continuous spin system 1-3 and a mean field Ising model 2,4,5 demonstrated that the hysteresis loop area A follows the scaling relation…”

Section: Introductionmentioning

confidence: 99%

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Magnetization reversal dynamics in epitaxial spin-valve structures

et al. 2000

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We report the dynamic hysteresis behavior of epitaxial single ferromagnetic NiFe, Co layers, and NiFe/Cu/Co spin-valve structures investigated as a function of field sweep rate Ḣ (dH/dt) in the range 0.01-270 kOe/sec using the magneto-optic Kerr effect. In situ reflection high-energy electron-diffraction images confirmed that the NiFe, Cu, and Co layers grew epitaxially in the ͑100͒ orientation where the fcc NiFe, Co͗110͘ in-plane directions correspond to the Si͗100͘ directions. For Cu/60 Å NiFe/Cu/Si (H c ϭ5 Oe) and Cu/40 Å Co/Cu/Si (H c ϭ104 Oe) single magnetic layer structures, the hysteresis loop area A is found to follow the scaling relation AϰḢ ␣ with ␣ϳ0.13 and ϳ0.02 at low sweep rates and ϳ0.70 and ϳ0.30 at high sweep rates, respectively. This result indicates that the NiFe and Co layers in the spin-valve structures can be expected to show distinct scaling behavior at high sweep rate. We found that the ''double-switching'' behavior which occurs at low sweep rates transforms to ''single switching'' at ϳ154 kOe/sec and ϳ192 kOe/sec, respectively, for the single and double spin valves due to the different dynamic response of the NiFe and Co layers. Our results provide direct experimental evidence that the magnetic anisotropy strength affects dynamic hysteresis scaling in ultrathin magnetic films, in contrast with the predictions of current theoretical models.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Magnetization reversal dynamics in epitaxial spin-valve structures

et al. 2000

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“…On the experimental picture, it can be said that a great many of experimental studies have been devoted to DPTs and hysteresis behaviors of Co films on a Cu (001) surface [32], [Co(4A o )/Pt(7A o )] multi-layer system with strong perpendicular anisotropy [33], thin polycrystalline Ni 80 Fe 20 films [34], ultrathin ferromagnetic Fe/Au(001) films [35], epitaxial Fe/GaAs(001) thin films [36], epitaxial single ferromagnetic fcc NiFe(001), fcc Co(001), and fcc NiFe/Cu/Co(001) layers [37], Fe 0.42 Zn 0.58 F 2 [38], finemet thin films [39], and epitaxial Fe/GaAs(001) and Fe/InAs(001) ultrathin films [40]. After some detailed experimental investigations, it has been observed that experimental non-equilibrium dynamics of considered real magnetic systems strongly resemble the dynamic behav-ior predicted from theoretical calculations of a kinetic Ising model.…”

Section: Introductionmentioning

confidence: 99%

Investigation of oscillation frequency and disorder induced dynamic phase transitions in a quenched-bond diluted Ising ferromagnet

Vatansever¹,

Akıncı²,

Yüksel³

et al. 2013

Journal of Magnetism and Magnetic Materials

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Frequency evolutions of hysteresis loop area and hysteresis tools such as remanence and coercivity of a kinetic Ising model in the presence of quenched bond dilution are investigated in detail. The kinetic equation describing the time dependence of the magnetization is derived by means of effectivefield theory with single-site correlations. It is found that the frequency dispersions of hysteresis loop area, remanence and coercivity strongly depend on the quenched bond randomness, as well as applied field amplitude and oscillation frequency. In addition, the shape of the hysteresis curves for a wide variety of Hamiltonian parameters is studied and some interesting behaviors are found. Finally, a comparison of our observations with those of recently published studies is represented and it is shown that there exists a qualitatively good agreement.

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“…The recent theoretical [5][6][7][8][9][10][11][12][13] and experimental [14] studies on the hysteresis (also see Ref. [4] and references therein) focus on two topics: the dynamic symmetry breaking, and the area of the hysteresis loop.…”

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Hysteresis loop area of the Ising model

2004

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The hysteresis of the Ising model in a spatially homogeneous AC field is studied using both mean-field calculations and two-dimensional Monte Carlo simulations. The frequency dispersion and the temperature dependence of the hysteresis loop area are studied in relation to the dynamic symmetry loss. The dynamic mechanisms may be different when the hysteresis loops are symmetric or asymmetric, and they can lead to a double-peak frequency dispersion and qualitatively different temperature dependence.PACS numbers: 75.60. Ej, 75.40.Gb, 75.10.Hk When a cooperative many-body system, such as a magnet, is placed in an oscillating external perturbation (such as a magnetic field), it may show also oscillating dynamic response. This response usually lags in time, creating a hysteresis loop with nonzero area. This phenomenon exists widely in, e.g., magnetic systems and ferroelectric systems [1], and has been arousing great interest for its important technical application and intriguing physics [2][3][4].The recent theoretical [5-13] and experimental [14] studies on the hysteresis (also see Ref.[4] and references therein) focus on two topics: the dynamic symmetry breaking, and the area of the hysteresis loop. The first phenomenon is due to the competing time scales in such nonequilibrium systems [4]: The hysteresis loop loses its symmetry when the time period of the oscillating external perturbation becomes much smaller than the typical relaxation time of the system. On the other hand, the interesting variance of the hysteresis loop area with such parameters as temperature and oscillation frequency can also be attributed to the time scale competition. For example, in the frequency dispersion of the loop area of the Ising model, the frequency ω 0 /2π giving the maximal area corresponds roughly to the point where a resonance occurs. When an Ising system is placed in an AC field, the dynamics may consist of domain nucleation and/or domain growth [3]. The nucleation rate of new domains can be predicted by a characteristic time τ n , and the domain growth rate is also linked with a characteristic time τ g . The resonance occurs when the time period of the external perturbation is comparable to either one of these time scales or a combination of them. As is shown below, the details of this dynamic time scale competition necessarily rely on the dynamic phase of the system.In the present work, we hope to help clarify the relationship of the two mentioned-above topics in the framework of the Ising model, with mean-field (MF) calculations and two-dimensional Monte-Carlo (MC) simulations. (The frequency range that receives the most attention here is within the discussion of the previous works using the same methods [4].) When the loops are symmetric, the system dynamics is controlled by a domain nucleation-and-growth mechanism. When the loops are asymmetric (especially when the magnetization is well above or below zero), throughout the system evolution we can observe most spins being in the same direction. The dynamics of the remainin...

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Dynamic scaling of magnetic hysteresis in micron-sized Ni80Fe20 disks

Cited by 28 publications

References 14 publications

Magnetization reversal dynamics in epitaxial spin-valve structures

Magnetization reversal dynamics in epitaxial spin-valve structures

Investigation of oscillation frequency and disorder induced dynamic phase transitions in a quenched-bond diluted Ising ferromagnet

Hysteresis loop area of the Ising model

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