Perpendicular magnetic anisotropy influence on voltage-driven spin-diode effect in magnetic tunnel junctions: A micromagnetic study

Frankowski, Marek; Chęciński, Jakub; Skowroński, Witold; Stobiecki, T.

doi:10.1016/j.jmmm.2016.12.099

Cited by 12 publications

(9 citation statements)

References 44 publications

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“…Such a behavior of ∆H and the decreased remanence with respect to the saturation magnetization (see, [17]) both confirm a strong angular dispersion of the easy PMA axis in both layers. It has been observed that with increasing PMA the dispersion of anisotropy also increases [6,7,27]. As a result, dispersion in PMA leads to a large two magnon scattering contribution to the linewidth for in-plane magnetization and to an enhanced Gilbert damping [6].…”

Section: Resultsmentioning

confidence: 99%

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CoFeB/MgO/CoFeB structures with orthogonal easy axes: perpendicular anisotropy and damping

Głowiński

Żywczak²,

Wrona³

et al. 2017

J. Phys.: Condens. Matter

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We report on the Gilbert damping parameter α, the effective magnetization [Formula: see text], and the asymmetry of the g-factor in bottom-CoFeB(0.93 nm)/MgO(0.90-1.25 nm)/CoFeB(1.31 nm)-top as-deposited systems. Magnetization of CoFeB layers exhibits a specific noncollinear configuration with orthogonal easy axes and with [Formula: see text] values of [Formula: see text] kG and [Formula: see text] kG for the bottom and top layers, respectively. We show that [Formula: see text] depends on the asymmetry [Formula: see text] of the g-factor measured in the perpendicular and the in-plane directions revealing a highly nonlinear relationship. In contrast, the Gilbert damping is practically the same for both layers. Annealing of the films results in collinear easy axes perpendicular to the plane for both layers. However, the linewidth is strongly increased due to enhanced inhomogeneous broadening.

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Section: Resultsmentioning

confidence: 99%

“…While ∆H 0 for the top layer is almost the same for both configurations, ∆H 0 for the bottom layer at the (b) configuration is nearly twice as large as that for the (a) configuration. Such a behavior suggests that the layer B is rather inhomogeneous with a large angular dispersion of magnetization across the layer [26,27].…”

Section: In-plane Configurationmentioning

confidence: 99%

CoFeB/MgO/CoFeB structures with orthogonal easy axes: perpendicular anisotropy and damping

Głowiński

Żywczak²,

Wrona³

et al. 2017

J. Phys.: Condens. Matter

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“…This behavior is expected, as for thicker t FL the absolute value of the effective magnetization is reduced and it is more susceptible to the anisotropy change induced by the electric field 23 . Moreover, in the same thickness regime, where the transition between perpendicular and in-plane anisotropy occurs, the effective damping increases, which may be attributed to an increase in the level of magnetization disorder 24 .…”

Section: Discussionmentioning

confidence: 94%

Understanding stability diagram of perpendicular magnetic tunnel junctions

Skowroński

Czapkiewicz

Ziętek

et al. 2017

Sci Rep

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Perpendicular magnetic tunnel junctions (MTJ) with a bottom pinned reference layer and a composite free layer (FL) are investigated. Different thicknesses of the FL were tested to obtain an optimal balance between tunneling magnetoresistance (TMR) ratio and perpendicular magnetic anisotropy. After annealing at 400 °C, the TMR ratio for 1.5 nm thick CoFeB sublayer reached 180% at room temperature and 280% at 20 K with an MgO tunnel barrier thickness corresponding to the resistance area product RA = 10 Ohmμm2. The voltage vs. magnetic field stability diagrams measured in pillar-shaped MTJs with 130 nm diameter indicate the competition between spin transfer torque (STT), voltage controlled magnetic anisotropy (VCMA) and temperature effects in the switching process. An extended stability phase diagram model that takes into account all three effects and the effective damping measured independently using broadband ferromagnetic resonance technique enabled the determination of both STT and VCMA coefficients that are responsible for the FL magnetization switching.

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“…Afterwards, MTJ resistance is calculated and multiplied by the assumed leakage current associated with the applied voltage, resulting in V mix , in the same way as in the experimental procedure. We used a similar approach previously in V-FMR spin diode effect modelled using micromagnetic simulations 27 .…”

Section: Resultsmentioning

confidence: 99%

“…2(d). At the same time, magnetic fields sufficient to saturate the sample would increase the effective field to the level where the VCMA excitation would no longer be strong enough to induce significant magnetization dynamics 27 . Therefore, we limit the V-FMR investigation to samples annealed at 250 and 300 • C.…”

Section: Resultsmentioning

confidence: 99%

High frequency voltage-induced ferromagnetic resonance in magnetic tunnel junctions

Skowroński

Łazarski

Mojsiejuk

et al. 2019

Applied Physics Letters

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Voltage-induced ferromagnetic resonance (V-FMR) in magnetic tunnel junctions (MTJs) with a W buffer is investigated. Perpendicular magnetic anisotropy (PMA) energy is controlled by both thickness of a CoFeB free layer deposited directly on the W buffer and a post-annealing process at different temperatures. The PMA energy as well as the magnetization damping are determined by analysing field-dependent FMR signals in different field geometries. An optimized MTJ structure enabled excitation of V-FMR at frequencies exceeding 30 GHz. The macrospin modelling is used to analyse the field-and angular-dependence of the V-FMR signal and to support experimental magnetization damping extraction.

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Perpendicular magnetic anisotropy influence on voltage-driven spin-diode effect in magnetic tunnel junctions: A micromagnetic study

Cited by 12 publications

References 44 publications

CoFeB/MgO/CoFeB structures with orthogonal easy axes: perpendicular anisotropy and damping

CoFeB/MgO/CoFeB structures with orthogonal easy axes: perpendicular anisotropy and damping

Understanding stability diagram of perpendicular magnetic tunnel junctions

High frequency voltage-induced ferromagnetic resonance in magnetic tunnel junctions

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