Contribution of low-temperature degrees of freedom to the anisotropy in Co/CoO exchange coupled bilayers

D. Venus; F. Hunte; E D Dahlberg

doi:10.1016/j.jmmm.2004.09.038

Contribution of low-temperature degrees of freedom to the anisotropy in Co/CoO exchange coupled bilayers

D. Venus, F. Hunte, E D Dahlberg

Physics and Astronomy (Twin Cities)

Research output: Contribution to journal › Article › peer-review

7 Scopus citations

Abstract

Measurements of the transverse magnetic AC-susceptibility χ(T) of exchange coupled polycrystalline Co/CoO bilayers have been made via the anisotropic magnetoresistance using a small AC field of 2-5 Oe and frequencies from 40 to 400 Hz. A step increase in Reχ is observed at 50-100 K, with an accompanying dissipation peak in Imχ. This feature is independent of the CoO thickness, but its dispersion with frequency suggests a thermally activated degree of freedom with an activation energy E _a∼150 K. This is consistent with a contribution to the anisotropy field due to the dynamics of the ferromagnetic rather than the antiferromagnetic grains.

Original language	English (US)
Pages (from-to)	191-195
Number of pages	5
Journal	Journal of Magnetism and Magnetic Materials
Volume	286
Issue number	SPEC. ISS.
DOIs	https://doi.org/10.1016/j.jmmm.2004.09.038
State	Published - Feb 2005

Keywords

Anisotropic magnetoresistance
Co/CoO
Exchange anisotropy
Exchange bias
Interfacial exchange
Magnetic susceptibility

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10.1016/j.jmmm.2004.09.038

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title = "Contribution of low-temperature degrees of freedom to the anisotropy in Co/CoO exchange coupled bilayers",

abstract = "Measurements of the transverse magnetic AC-susceptibility χ(T) of exchange coupled polycrystalline Co/CoO bilayers have been made via the anisotropic magnetoresistance using a small AC field of 2-5 Oe and frequencies from 40 to 400 Hz. A step increase in Reχ is observed at 50-100 K, with an accompanying dissipation peak in Imχ. This feature is independent of the CoO thickness, but its dispersion with frequency suggests a thermally activated degree of freedom with an activation energy E a∼150 K. This is consistent with a contribution to the anisotropy field due to the dynamics of the ferromagnetic rather than the antiferromagnetic grains.",

keywords = "Anisotropic magnetoresistance, Co/CoO, Exchange anisotropy, Exchange bias, Interfacial exchange, Magnetic susceptibility",

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T1 - Contribution of low-temperature degrees of freedom to the anisotropy in Co/CoO exchange coupled bilayers

AU - Venus, D.

AU - Hunte, F.

AU - Dahlberg, E D

PY - 2005/2

Y1 - 2005/2

N2 - Measurements of the transverse magnetic AC-susceptibility χ(T) of exchange coupled polycrystalline Co/CoO bilayers have been made via the anisotropic magnetoresistance using a small AC field of 2-5 Oe and frequencies from 40 to 400 Hz. A step increase in Reχ is observed at 50-100 K, with an accompanying dissipation peak in Imχ. This feature is independent of the CoO thickness, but its dispersion with frequency suggests a thermally activated degree of freedom with an activation energy E a∼150 K. This is consistent with a contribution to the anisotropy field due to the dynamics of the ferromagnetic rather than the antiferromagnetic grains.

AB - Measurements of the transverse magnetic AC-susceptibility χ(T) of exchange coupled polycrystalline Co/CoO bilayers have been made via the anisotropic magnetoresistance using a small AC field of 2-5 Oe and frequencies from 40 to 400 Hz. A step increase in Reχ is observed at 50-100 K, with an accompanying dissipation peak in Imχ. This feature is independent of the CoO thickness, but its dispersion with frequency suggests a thermally activated degree of freedom with an activation energy E a∼150 K. This is consistent with a contribution to the anisotropy field due to the dynamics of the ferromagnetic rather than the antiferromagnetic grains.

KW - Anisotropic magnetoresistance

KW - Co/CoO

KW - Exchange anisotropy

KW - Exchange bias

KW - Interfacial exchange

KW - Magnetic susceptibility

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U2 - 10.1016/j.jmmm.2004.09.038

DO - 10.1016/j.jmmm.2004.09.038

M3 - Article

AN - SCOPUS:11444262352

SN - 0304-8853

VL - 286

SP - 191

EP - 195

JO - Journal of Magnetism and Magnetic Materials

JF - Journal of Magnetism and Magnetic Materials

IS - SPEC. ISS.

ER -

Contribution of low-temperature degrees of freedom to the anisotropy in Co/CoO exchange coupled bilayers

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