Soniscan: A ferroacoustic thin-film memory

In magnetostrictive thin films, distinctive types of anisotropy skew patterns are found. These patterns depend on (i) the sign of the film's magnetostriction constant and (ii) the coefficient of thermal expansion of the film relative to that of its substrate. It is shown that these effects can be explained by the presence of thermal gradients in the film-substrate structure during and following the deposition process. Using the theory of magnetostrictively induced anisotropy in thin films, expressions for the variation in anisotropy field and easy-axis direction due to temperature gradients are derived and compared with those found experimentally. In order to restrict magnetostrictively induced easy-axis skews to ±0.5°, temperature gradients must be less than 0.5°K/cm.

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Ultrasound induced irreversible changes in the magnetization of highly magnetostrictive materials Tb0.27Dy0.73Fe2 and MnBi

Winter

Arrott

1982

Journal of Applied Physics

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A sample, after being saturated in a high magnetic field, is in an unstable remanent state in a low or reversed magnetic field. Application of a burst of ultrasound at this point will result in an irreversible decrease in the remanent magnetization. By subsequently changing the magnetic field, and applying a second burst of ultrasound, a reduced irreversible decrease is effected. This observed behavior is a measure of the statistical correlation between the two magnetic states of the sample. We have successfully described this behavior with a modified Preisach model. We have observed irreversible changes in the magnetization of Tb0.27Dy0.73Fe2 (λ111 = 1.6×10−3) as large as 50% of the remanent magnetization, or 0.4% of the saturation magnetization, induced by ultrasound bursts of 107 dyne/cm2 at 20 °C. In MnBi (λs = −8×10−4) crystals in Bi, irreversible effects as large as 1.8% of the remanent magnetization, or 0.6% of the saturation magnetization, have been observed at 120 K.

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Soniscan: A ferroacoustic thin-film memory

Cited by 6 publications

References 13 publications

Magnetic Thin Film Devices

Magnetic Thin Film Devices

Theory of anisotropy skew in magnetostrictive thin films

Ultrasound induced irreversible changes in the magnetization of highly magnetostrictive materials Tb0.27Dy0.73Fe2 and MnBi

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