Magnetic interlayer coupling in ferromagnet/insulator/ferromagnet structures

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Abstract

Magnetic coupling between (Formula presented) (CoFe) and (Formula presented) (NiFe) thin films separated by a (Formula presented) layer was investigated with magnetization measurements, Mössbauer spectroscopy, and Lorentz imaging. (Formula presented) thicknesses varied from 0 to 1000 Å. When the spacer layer was thicker than 10 Å, separate reversal of the magnetic layers was observed in the hysteresis loops. The coercivity of a 300 Å NiFe film separated from a 300 Å CoFe film by 20 Å of (Formula presented) was about 50 Oe, compared to 1 Oe for a free NiFe layer. The coercive field of the NiFe decreased and the magnetization reversal became sharper with increasing (Formula presented) thickness. The NiFe showed an enhanced coercivity even with a demagnetized CoFe layer, suggesting that domain walls contribute to the coupling. Mössbauer measurements in zero applied field confirmed that the spin dispersion of the NiFe layer resembled the CoFe dispersion in strongly coupled trilayers, but that the NiFe spins were nearly collinear with the easy axis in trilayers with small coupling. Lorentz imaging of single magnetic layer samples showed a complex, immobile domain-wall structure in the CoFe, but only ripple structure was observed in the NiFe. The Lorentz images of trilayers suggested that magnetostatic coupling between domain walls in the CoFe and induced walls and ripple structure in the NiFe resulted in the enhanced NiFe coercivity.

Original languageEnglish (US)
Pages (from-to)9633-9641
Number of pages9
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume61
Issue number14
DOIs
StatePublished - Jan 1 2000

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Magnetic couplings
Domain walls
Coercive force
interlayers
insulators
Imaging techniques
Magnetization reversal
Magnetostatics
coercivity
domain wall
Hysteresis loops
ripples
Magnetization
Spectroscopy
Thin films
magnetization
magnetostatics
spacers
hysteresis
thin films

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Magnetic interlayer coupling in ferromagnet/insulator/ferromagnet structures. / Platt, C.; McCartney, Martha.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 61, No. 14, 01.01.2000, p. 9633-9641.

Research output: Contribution to journalArticle

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abstract = "Magnetic coupling between (Formula presented) (CoFe) and (Formula presented) (NiFe) thin films separated by a (Formula presented) layer was investigated with magnetization measurements, M{\"o}ssbauer spectroscopy, and Lorentz imaging. (Formula presented) thicknesses varied from 0 to 1000 {\AA}. When the spacer layer was thicker than 10 {\AA}, separate reversal of the magnetic layers was observed in the hysteresis loops. The coercivity of a 300 {\AA} NiFe film separated from a 300 {\AA} CoFe film by 20 {\AA} of (Formula presented) was about 50 Oe, compared to 1 Oe for a free NiFe layer. The coercive field of the NiFe decreased and the magnetization reversal became sharper with increasing (Formula presented) thickness. The NiFe showed an enhanced coercivity even with a demagnetized CoFe layer, suggesting that domain walls contribute to the coupling. M{\"o}ssbauer measurements in zero applied field confirmed that the spin dispersion of the NiFe layer resembled the CoFe dispersion in strongly coupled trilayers, but that the NiFe spins were nearly collinear with the easy axis in trilayers with small coupling. Lorentz imaging of single magnetic layer samples showed a complex, immobile domain-wall structure in the CoFe, but only ripple structure was observed in the NiFe. The Lorentz images of trilayers suggested that magnetostatic coupling between domain walls in the CoFe and induced walls and ripple structure in the NiFe resulted in the enhanced NiFe coercivity.",
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AB - Magnetic coupling between (Formula presented) (CoFe) and (Formula presented) (NiFe) thin films separated by a (Formula presented) layer was investigated with magnetization measurements, Mössbauer spectroscopy, and Lorentz imaging. (Formula presented) thicknesses varied from 0 to 1000 Å. When the spacer layer was thicker than 10 Å, separate reversal of the magnetic layers was observed in the hysteresis loops. The coercivity of a 300 Å NiFe film separated from a 300 Å CoFe film by 20 Å of (Formula presented) was about 50 Oe, compared to 1 Oe for a free NiFe layer. The coercive field of the NiFe decreased and the magnetization reversal became sharper with increasing (Formula presented) thickness. The NiFe showed an enhanced coercivity even with a demagnetized CoFe layer, suggesting that domain walls contribute to the coupling. Mössbauer measurements in zero applied field confirmed that the spin dispersion of the NiFe layer resembled the CoFe dispersion in strongly coupled trilayers, but that the NiFe spins were nearly collinear with the easy axis in trilayers with small coupling. Lorentz imaging of single magnetic layer samples showed a complex, immobile domain-wall structure in the CoFe, but only ripple structure was observed in the NiFe. The Lorentz images of trilayers suggested that magnetostatic coupling between domain walls in the CoFe and induced walls and ripple structure in the NiFe resulted in the enhanced NiFe coercivity.

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