Inductance fluctuation, domain instability and popcorn noise in thin film heads

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

doi:10.1109/20.333933

Cited by 7 publications

(4 citation statements)

References 11 publications

(3 reference statements)

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“…Thus, by measuring the inductance fluctuations of micro Flexhead® components under DC bias current, one can infer their susceptibilities to Barkhausen wall jumps, and thus popcorn noise probabilities. This result is consistent with that observed in conventional thin film heads [9].…”

supporting

confidence: 93%

“…In addition to the above investigations of popcorn noise mechanisms, the susceptibilities of micro Flexhead® components to Barkhausen wall jumps. thus to popcorn noise, were also measured electrically as inductance fluctuations under DC bias current [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

“…Armed with the above understanding of the mechanisms of popcorn noise, the susceptibilities of micro Flexhead® components to Barkhausen wall jumps, thus to popcorn noise, were also measured electrically as inductance fluctuations under DC bias current [9]. Large inductance fluctuations in head A, as observed in Fig.…”

mentioning

confidence: 99%

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Popcorn Noise in Micro Flexbead<sup>®</sup> Components

Liu

Louis²,

Anderson³

et al. 1994

J. Magn. Soc. Jpn.

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---The effects of thermal transients after write, changes in stress-magnetostriction products and dynamic domain instabilities on popcorn noise probabilities in micro Flexhead® components were studied., It was observed that popcorn noise probabilities in micro Flexhead® components increase as the write current duration increases, until they saturate, with a specific write current amplitude. With increasing write current amplitude, the initial rate of change of noise probability with write current duration increases. In some cases where the resultant stress-magnetostriction products in micro Flexhead® components are negative, popcorn noise probabilities were observed to increase exponentially as functions of applied stress gradients. High rates of occurrence of dynamic domain instabilities have also been correlated with micro Flexhead® components that have high popcorn noise probabilities. Therefore. high probabilities of popcorn noise in micro Flexhead® components are caused by the combined effects of thermal transients after write, changes in stress-magnetostriction products and dynamic domain instabilities. Finally. an inductance fluctuation measurement technique was shown to be useful in quickly detecting micro Flexhead® components that are susceptible to popcorn noise.

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supporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

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Popcorn Noise in Micro Flexbead<sup>®</sup> Components

Liu

Louis²,

Anderson³

et al. 1994

J. Magn. Soc. Jpn.

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“…Sharp transitions in the read back signal following a write operation (popcorn noise) are caused by a wall in motion overcoming abruptly a defect in a yoke [1], [2]. Wiggles at the trailing edge in the read back signal can also be present during a read long after a write when the domain walls in shields are incidentally driven by excitation signals from the media [1].…”

Section: Introductionmentioning

confidence: 97%

Stray Field Dependent Reader Noise in Thin-Film Heads

et al. 2004

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The stray field magnitude and distribution, at sensor level, have been investigated as a function of the thickness of the shield, the presence of a domain wall in the shield, the relative position of the vortex accompanying the wall and its proximity to the Air-Bearing-Surface (ABS). Using micromagnetics, the stray fields at the reader sensor have been simulated while a domain wall moves in a shield near the ABS in a magnetic head. For shield thicknesses from 640 nm to 1280 nm, a range of interest for head design, the domain wall shape is C-shaped with a vortex-like structure on either side of the domain wall that provides flux closure inside the film. For a 5 Oe incidental field, the wall exits at the ABS in less than 20 ns when the wall is between the ABS and the vortex. Average stray fields reached 60 Oe while 100 Oe localized stray fields are observed as the wall exits the ABS. The dynamics of wall motion change when the vortex is between the ABS and the domain wall. A 5 Oe incidental field in a 640 nm thick shield drove the wall toward the ABS, compressing the vortex and creating a blocking structure. An incidental 10 Oe field twisted the wall center magnetization enough to change wall chirality accelerating the wall exit, preventing the blocking structure, and flipping the vortex to the other side of the wall. Average stray fields are 55 Oe with a local maximum of 70 Oe. Similar results occur for a 1280 nm thick shield for a 5 Oe field, with average stray fields of 60 Oe and a local maximum of 100 Oe.

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