Carbon: A bane for giant magnetoresistance magnetic multilayers

Yang, David; Chopra, Harsh Deep; Shashishekar, B.; Chen, P. J.; Egelhoff, William F.

doi:10.1063/1.1469682

Cited by 2 publications

(1 citation statement)

References 10 publications

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“…As an illustration, recent growth studies have led to an improved understanding of the role of surfactants in controlling interface structure at the atomic scale. Such effects can be used to dramatically influence magnetic properties in ultrathin films by controlling the interface roughness-for example, the surfactant effect of minute amounts of oxygen in the 10 −9 mbar range can significantly affect the magnitude of the giant magnetoresistance in spin-valve structures [134], while 1-3 at% carbon in Co/Cu spin-valves can eliminate the GMR effect altogether [135,136]. Submonolayer coverages of non-magnetic materials can change the magnetic anisotropy of ultrathin films, in some cases causing a complete reorientation of the magnetic easy axis [137][138][139][140].…”

Section: An Introduction To the Physics Of Magnetism In Ultrathin Filmsmentioning

confidence: 99%

Magnetism in ultrathin film structures

Vaz¹,

Bland²,

2008

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In this paper, we review some of the key concepts in ultrathin film magnetism which underpin nanomagnetism. We survey the results of recent experimental and theoretical studies of well characterized epitaxial structures based on Fe, Co and Ni to illustrate how intrinsic fundamental properties such as the magnetic exchange interactions, magnetic moment and magnetic anisotropies change markedly in ultrathin films as compared with their bulk counterparts, and to emphasize the role of atomic scale structure, strain and crystallinity in determining the magnetic properties. After introducing the key length scales in magnetism, we describe the 2D magnetic phase transition and survey studies of the thickness dependent Curie temperature and the critical exponents which characterize the paramagnetic-ferromagnetic phase transition. We next discuss recent experimental and theoretical results on the determination of the exchange constant, followed by an overview of measurements of the magnetic moment in the elemental 3d transition metal thin films in the various crystal phases that have been successfully stabilized, thereby illustrating the sensitivity of the magnetic moment to the local symmetry and to the atomic environment. Finally, we discuss briefly the magnetic anisotropies of Fe, Co and Ni in the fcc crystalline phase, to emphasize the role of structure and the details of the interface in influencing the magnetic properties. The dramatic effect that adsorbates can have on the magnetic anisotropies of thin magnetic films is also discussed. Our survey demonstrates that the fundamental properties, namely, the magnetic moment and magnetic anisotropies of ultrathin films have dramatically different behaviour compared with those of the bulk while the comparable size of the structural and magnetic contributions to the total energy of ultrathin structures results in an exquisitely sensitive dependence of the magnetic properties on the film structure.

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Section: An Introduction To the Physics Of Magnetism In Ultrathin Filmsmentioning

confidence: 99%

Magnetism in ultrathin film structures

Vaz¹,

Bland²,

2008

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Highly deleterious role of small amounts of carbon on the giant magnetoresistance effect

Yang

Repetski

Chopra

et al. 2003

Journal of Applied Physics

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Carbon (in the form of hydrocarbons) is a common contaminant in high and ultra-high-vacuum systems, and easily gets incorporated in films during deposition. This work reports the highly deleterious role of small amounts of carbon on the structure and magnetic properties of “giant” magnetoresistance (GMR) spin valves. Controlled incorporation of 1–3 at. % carbon in Co/Cu layers of NiO–Co–Cu-based spin valves has been found to completely eliminate the GMR effect. Transmission electron microscopy (TEM) shows that carbon promotes highly discontinuous Co/Cu layers, resulting in a large number of pinholes; domain studies corroborate that the “free” layer under the influence of a large pinhole coupling is unable to switch independently of the “pinned” Co layer. These results also have implications for other multilayers and spintronics devices.

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Carbon: A bane for giant magnetoresistance magnetic multilayers

Cited by 2 publications

References 10 publications

Magnetism in ultrathin film structures

Magnetism in ultrathin film structures

Highly deleterious role of small amounts of carbon on the giant magnetoresistance effect

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