Exchange bias and magnetization process of Co/CoO nanocomposite thin films

Yi, Jiabao; Ding, Jun; Liu, Bing Hai; Dong, Zhili; White, Timothy John; Liu, Y.

doi:10.1016/j.jmmm.2004.07.044

Cited by 19 publications

(5 citation statements)

References 29 publications

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“…This has similar characteristics to the one obtained in Ref. 30. Around the Ni coercive field, the magnetization of the ferromagnetic layers is in the antiparallel configuration, as shown in Fig.…”

Section: A Nb/co Bilayerssupporting

confidence: 87%

Vortex flipping in superconductor/ferromagnet spin-valve structures

et al. 2013

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We report in-plane magnetization measurements on Ni/Nb/Ni/CoO and Co/Nb/Co/CoO spin valve structures with one of the ferromagnetic layers pinned by an antiferromagnetic layer. In samples with Ni below the superconducting transition T c , our results show strong evidence of vortex flipping driven by ferromagnet magnetization. This is a direct consequence of the proximity effect that leads to vortex supercurrent leakage into the ferromagnets. Here, the polarized electron spins are subject to the vortices' magnetic field, occasioning vortex flipping. Such a novel mechanism has been made possible by fabrication of the ferromagnet/superconductor/ferromagnet/antiferromagnet multilayered spin valves with an S layer thin enough to barely confine vortices inside as well as F layers thin enough to align and control magnetization within the plane. When Co is used, the vortex flipping effect is not observed. This is attributed to the shorter coherence length of Co. Interestingly, a reduction in the pinning field of about 400 Oe is observed instead when the Nb layer is in the superconducting state. This effect cannot be explained in terms of vortex fields. In view of these facts, any explanation must be directly related to the proximity effect and thus a remarkable phenomenon that deserves further investigation.

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Section: A Nb/co Bilayerssupporting

confidence: 87%

Vortex flipping in superconductor/ferromagnet spin-valve structures

et al. 2013

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“…3, it is also evident that for all the Co films in zone (I), the CoO layers occupy almost the whole volume of the film, or thickness corresponding to zone (I): i.e., 2 ranges from 70% to 100%. Moreover, it is known that the lattice constant of FCC CoO is [5]. Hence, in the CoO/Co or the Co/glass interface, the lattice strain is estimated to be %.…”

Section: Resultsmentioning

confidence: 99%

“…T HE properties and applications of Co films have already been extensively studied [1]- [5]. For example, thick Co films have been investigated in many aspects.…”

Section: Introductionmentioning

confidence: 99%

Magnetic properties of face-centered cubic Co films

et al. 2006

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We deposited face-centered cubic (FCC) Co films on glass substrates by sputtering. From Auger-depth profile analysis, we found that there is one CoO layer, about 13 A thick, lying on the top surface of the Co film, and another CoO layer, about 37 A thick, lying within the Co/glass interface. At room temperature, the thin CoO film is supposed to be paramagnetic. However, because of the proximity effect between CoO and Co, the CoO layer may become ferromagnetic, with saturation magnetization . By fitting the saturation magnetization ( ) data of the whole Co/CoO film as a function of (1 ), where is the Co thickness, we can prove that the last conjecture is correct, and the of the CoO layer is indeed not zero. Both the dependence of the magnetostriction constant ( ) and the dependence of the coercive field ( ) show a two-region characteristic. The dividing line for the former quantity is at = 88 A, and for the latter it is at = 120 A. When crossing such a dividing line, there is a discontinuous jump in (or ). These phenomena occur because the lattice-strain and magnetoelastic effects within the CoO layer dominate the and the behavior in ultra-thin ( 88 A) Co films. In this region, the roughness-to-thickness ratio ( ) may also affect . Finally, there seems to be no connection between the grain size ( ) and .Index Terms-Co film, magnetostriction, proximity effect.

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“…Furthermore, the effect of interaction between CoO phases on the exchange bias and coercive field were also studied. It showed that with the decreasing of the interaction (dipolar, exchange), the exchange bias decreases [11,12]. It is believed that the exchange interaction of the atoms becomes weak with less ordering of the antiferromagnet, the exchange anisotropy of the system may also decrease.…”

Section: Introductionmentioning

confidence: 99%