Perpendicular magnetic tunnel junctions using Co-based multilayers

Tadisina, Zeenath Reddy; Natarajarathinam, Anusha; Clark, Billy D.; Highsmith, Alton L.; Mewes, Tim; Gupta, Subhadra; Chen, E.; Wang, S.

doi:10.1063/1.3358242

Cited by 38 publications

(10 citation statements)

References 16 publications

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“…This is an alternative exciting approach to fully perpendicular MTJ's using multilayers, L1 0 materials, or amorphous RE-TM materials, for which it is much more difficult to achieve high TMR ratios than for in-plane devices. 18 …”

Section: Introductionmentioning

confidence: 99%

Influence of capping layers on CoFeB anisotropy and damping

Natarajarathinam

Tadisina

Mewes

et al. 2012

Journal of Applied Physics

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Magnetic behavior of CoFeB at various thicknesses ranging from 2 nm to 8 nm capped with different materials, such as MgO, Ta, Ru, and V have been studied. The films were sputter-deposited and subsequently characterized by magnetometry and broadband ferromagnetic resonance (FMR). There are magnetically dead layers at the interface observed with Ru and Ta capping layers, while MgO and V have almost no effect on the magnetization of the CoFeB. As the ferromagnetic layer is made thinner, the effective magnetization decreases, indicating an interfacial perpendicular anisotropy. Particularly in the case of MgO, V/Ru, and V/Ta capping layers, interfacial perpendicular anisotropy is induced in CoFeB, and the Gilbert damping parameter is also reduced. The origin of this perpendicular magnetic anisotropy (PMA) is understood to be caused by the interface anisotropy between the free layer and the capping layer. The effect of post-deposition annealing and CoFeB thickness on the anisotropy and damping of V/Ta capped samples are reported. Doping CoFeB with vanadium (V) greatly reduced the 4πMs and 4πMeff values, resulting in an effective increase in the PMA.

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Section: Introductionmentioning

confidence: 99%

Influence of capping layers on CoFeB anisotropy and damping

Natarajarathinam

Tadisina

Mewes

et al. 2012

Journal of Applied Physics

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“…There have been a number of reports on pMTJ film stacks using various perpendicular materials, including L1 0 -ordered FePt, 8 CoFe/Pd, 9,10 Co/Pd, [11][12][13] and Co/Pt. 14,15 While L1 0 -ordered FePt provides strong crystalline anisotropy and is compatible with high temperature annealing, 8 the L1 0 phase ordering temperature of FePt is typically above 400 C, requiring high-temperature deposition.…”

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confidence: 99%

Ultra-thin Co/Pd multilayers with enhanced high-temperature annealing stability

Gottwald

Lee

Kan

et al. 2013

Applied Physics Letters

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Understanding the thermal budget of perpendicular materials is crucial for the potential application perpendicular magnetic tunnel junctions. In this paper, we study the effects of high-temperature rapid thermal annealing on the structural and magnetic properties of ultra-thin Co/Pd multilayers deposited at room temperature. It is shown that perpendicular magnetic anisotropy of ultra-thin Co/Pd multilayers improves with increasing annealing temperature up to 425 °C. This property of ultra-thin Co/Pd multilayers provides increased thermal budgets for CMOS-integrated magnetic devices.

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“…This has important consequences for the effective anisotropies that one extracts from the dynamical data. The Kittel equations for systems with a second-and fourth-order perpendicular anisotropy are given by [33,42]:…”

Section: Influence Of the Length Scale Of Lateral Anisotropy Variamentioning

confidence: 99%

Inhomogeneous perpendicular magnetic anisotropy as a source of higher-order quasistatic and dynamic anisotropies

et al. 2018

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We investigate the influence of lateral variations of the second-order perpendicular anisotropy in thin films on the effective anisotropies required to represent this structure using a macrospin approximation. Second-order and fourth-order effective anisotropies are required for the macrospin approximation. In the case of quasi-static calculations, the fourth-order effective anisotropy is closely linked to deviations of the average magnetization angle from the field direction and lateral variations of the magnetization direction in the structure leading to dependence on the field strength and the lateral length scale of anisotropy variations of the effective anisotropies. We find that the field and lateral length scale dependence of the effective anisotropies extracted from simulations of the magnetization dynamics are profoundly different from those of the quasi-static simulations. This is caused by resonance localization that depends on the orientation of the external magnetic field.

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Perpendicular magnetic tunnel junctions using Co-based multilayers

Cited by 38 publications

References 16 publications

Influence of capping layers on CoFeB anisotropy and damping

Influence of capping layers on CoFeB anisotropy and damping

Ultra-thin Co/Pd multilayers with enhanced high-temperature annealing stability

Inhomogeneous perpendicular magnetic anisotropy as a source of higher-order quasistatic and dynamic anisotropies

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