Dynamic hysteresis behavior in epitaxial spin-valve structures

Lee, W. Y.; Samad, A.; Moore, T. A.; Bland, J. A. C.; Choi, Byoung Kyu

doi:10.1063/1.372783

Cited by 13 publications

(8 citation statements)

References 22 publications

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“…In the high dynamic regime, nucleation was considered to be the dominant reversal mechanism. The results of Lee et al for single Co and NiFe layers [48,49], and for Fe/GaAs(001) and Fe/InAs(001) [18,47], were qualitatively in good agreement with the experimental results and theoretical model of Raquet et al Hence the differing values of the exponent α between the two distinct regions were attributed to the change of reversal mechanism from domain wall motion to nucleation with increasing sweep rate. The main difference between the results of Lee et al and those of Raquet et al was that, instead of a sharp transition from the low to the high dynamic regime, a broad transition region over a small range of sweep rate (typically 10 kOe s −1 for Fe/GaAs(001) thin films) occurred.…”

Section: Experimental Backgroundsupporting

confidence: 79%

“…Since the models do not consider domain wall coercivity-dominated magnetization reversal processes, it is not really surprising that they are not supported by these experiments. With the work of Raquet et al [17,51] and, in our group, Lee et al [18,[47][48][49], evidence was obtained relating to a phenomenon seen much earlier by Kryder and Humphrey [21]. The loop area scaling in epitaxial Fe/GaAs(001) and Fe/InAs(001) thin films [18,47], and in epitaxial single ferromagnetic NiFe and Co layers [48,49] was investigated.…”

Section: Experimental Backgroundmentioning

confidence: 83%

“…With the work of Raquet et al [17,51] and, in our group, Lee et al [18,[47][48][49], evidence was obtained relating to a phenomenon seen much earlier by Kryder and Humphrey [21]. The loop area scaling in epitaxial Fe/GaAs(001) and Fe/InAs(001) thin films [18,47], and in epitaxial single ferromagnetic NiFe and Co layers [48,49] was investigated. In all cases, the hysteresis loop area A was found to follow equation (8).…”

Section: Experimental Backgroundmentioning

confidence: 83%

“…where Ḣ is the applied field sweep rate. Both the scaling relations equations ( 7) and ( 8) have been used by experimentalists to fit to data and thereby to determine the exponents α and β to compare with the theoretical models [18,[42][43][44][45][46][47][48][49][50]. The continuum models are relevant to small, insulating, defect-free, single-domain particles with a very small magnetic anisotropy, whilst the Ising models are relevant to ferromagnetic thin films with strong uniaxial anisotropy.…”

Section: Theoretical Descriptionsmentioning

confidence: 99%

“…In the last ten years, experimental studies of dynamic hysteresis in thin magnetic films have often used the power laws for loop area scaling for analysis of data [18,[42][43][44][45][46][47][48][49][50]. The first systematic experiments were made by He and Wang in 1993 [42].…”

Section: Experimental Backgroundmentioning

confidence: 99%

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Mesofrequency dynamic hysteresis in thin ferromagnetic films

Moore¹,

Bland

2004

J. Phys.: Condens. Matter

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The spectrum of timescales for thin film magnetization reversal processes from 10 3 to 10 −15 s is reviewed as well as appropriate experimental techniques for their investigation. The present review is motivated by the fact that most studies of magnetization dynamics have used polycrystalline NiFe thin films, whilst the magnetization dynamics of epitaxial Fe thin films, in contrast, have been little investigated, especially in the mesofrequency range (10 −1 -10 −6 s). Here, the competition between domain nucleation and domain wall propagation reversal processes results in a rich variety in the dynamical behaviour. We review the results of our time-resolved magneto-optic Kerr effect measurement of the dynamic hysteresis loop in epitaxial Fe thin films. Coercivity as a function of applied field frequency H c ( f ) is measured from the dynamic hysteresis loop in the frequency range ∼0.03-3000 Hz, corresponding to experimental timescales t exp ≈ H c / Ḣ in the range ∼10 −1 -10 −6 s, where Ḣ is the applied field sweep rate at the static coercive field H c . Not only are two distinct dynamic regimes for H c ( f ) found to arise in the experimental timescale range 10 −1 -10 −6 s, but also the reversal processes of domain nucleation and wall propagation are seen to compete at the crossover between the two dynamic regimes, so determining the behaviour of H c ( f ). This review gives a historical overview of dynamic hysteresis in the mesofrequency range, and surveys recent theoretical descriptions and experiments. It is demonstrated that dynamic hysteresis experiments on thin ferromagnetic films are richly informative of the magnetization dynamics in the mesofrequency range. Methods for the interpretation of dynamic coercive field measurements H c ( f ) are highlighted, including an adaptation of an existing model of magnetization reversal dynamics in ultrathin magnetic layers.

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