High frequency dynamic imaging of domains in thin film heads

Liu, F.H.; Schultz, Mark; Kryder, M.H.

doi:10.1109/20.104368

Cited by 19 publications

(4 citation statements)

References 10 publications

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“…This approach is based on a principle used earlier in high-speed domain wall dynamics studies. 37,38,40 The setup has 1μm spatial resolution. In the experiment, a single 100-2100 fs optical pump pulse was used to excite the films (see Fig.…”

Section: A Experimental Techniquementioning

confidence: 99%

All-optical magnetization reversal by circularly polarized laser pulses: Experiment and multiscale modeling

et al. 2012

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We present results of detailed experimental and theoretical studies of all-optical magnetization reversal by single circularly-polarized laser pulses in ferrimagnetic rare earth-transition metal (RE-TM) alloys Gd x Fe 90−x Co 10 (20% < x < 28%). Using single-shot time-resolved magneto-optical microscopy and multiscale simulations, we identified and described the unconventional path followed by the magnetization during the reversal process. This reversal does not involve precessional motion of magnetization but is governed by the longitudinal relaxation and thus has a linear character. We demonstrate that this all-optically driven linear reversal can be modeled as a result of a two-fold impact of the laser pulse on the medium. First, due to absorption of the light and ultrafast laser-induced heating, the medium is brought to a highly nonequilibrium state. Simultaneously, due to the ultrafast inverse Faraday effect the circularly polarized laser pulse acts as an effective magnetic field of the amplitude up to ∼20 T. We show that the polarization-dependent reversal triggered by the circularly polarized light is feasible only in a narrow range (below 10%) of laser fluences. The duration of the laser pulse required for the reversal can be varied from ∼40 fs up to at least ∼1700 fs. We also investigate experimentally the role of the ferrimagnetic properties of GdFeCo in the all-optical reversal. In particular, the optimal conditions for the all-optical reversal are achieved just below the ferrimagnetic compensation temperature, where the magnetic information can be all-optically written by a laser pulse of minimal fluence and read out within just 30 ps. We argue that this is the fastest write-read event demonstrated for magnetic recording so far.

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Section: A Experimental Techniquementioning

confidence: 99%

All-optical magnetization reversal by circularly polarized laser pulses: Experiment and multiscale modeling

et al. 2012

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“…From the recording side, direct observation of the thermomagnetic writing of information bits on a spinning MO disk by MO microscopy [8] and the 2D imaging of the magnetization dynamics in miniature thin film heads [29] have been performed at a ns scale. More recently, MO imaging of the magnetization reversal process at a sub-ns scale has been shown on mm size permalloy structures [30].…”

Section: Dynamical Measurementsmentioning

confidence: 99%

Magneto-Optical Studies of Magnetic Ultrathin Film Structures

Ferré¹,

Jamet

Meyer

1999

phys. stat. sol. (a)

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The specificities and advantages of magneto‐optics (MO) for studying the magnetism of thin film structures: sensitivity, high space and time resolution, and wavelength discrimination, are reviewed. Based on MO imaging experiments, two fundamental studies on the dynamics of the magnetization reversal in an ultrathin cobalt magnetic layer with perpendicular anisotropy and related dot arrays, or of the thermomagnetic MO recording–writing process, are presented.

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“…These systems were used for the investigation of magnetic bubble dynamics, 4,5 and later for studies on excited recording write heads. [6][7][8][9][10] Two fundamental methods, scanning and wide-field microscopy, were applied. In contrast to wide-field Kerr microscopy ͑where an image of a certain area is gained immediately͒, scanning microscopy probes the magnetization only at a small surface area with a focused laser beam.…”

Section: Introductionmentioning

confidence: 99%

Small-amplitude magnetization dynamics in permalloy elements investigated by time-resolved wide-field Kerr microscopy

et al. 2005

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A wide-field polarization microscope, optimized for Kerr microscopy was extended with a mode-locked pulsed laser illumination source to investigate time-dependent magnetization processes with picosecond resolution, thus providing the possibility to directly compare the quasistatic with the dynamic magnetization response. Square-shaped Ni 81 Fe 19 elements were excited by fast magnetic field pulses aligned along and diagonally to the elements, respectively. Starting from the Landau ground state, the magnetic response to the excitation is dominated by a fast rotation of magnetization followed by slow relaxation, mostly through domain wall motion, back into the Landau state. Spike domains in the corners of the element form during the fast rotational process. Low angle domains with oscillatory behavior develop in the low dynamic permeability closure domains. Slow motion of the center vortex over several nanoseconds is recorded. The direct comparison of the dynamic and the static domain patterns is necessary for a understanding of all details of the magnetization processes.

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High frequency dynamic imaging of domains in thin film heads

Cited by 19 publications

References 10 publications

All-optical magnetization reversal by circularly polarized laser pulses: Experiment and multiscale modeling

All-optical magnetization reversal by circularly polarized laser pulses: Experiment and multiscale modeling

Magneto-Optical Studies of Magnetic Ultrathin Film Structures

Small-amplitude magnetization dynamics in permalloy elements investigated by time-resolved wide-field Kerr microscopy

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