(a) Real-time voltage measured at the scope for +1 V dc bias across the MTJ and μ 0H oop = μ 0H s. Dwell time measurement results for θ H = 0° (μ 0H in = 0 mT). These observations are accurately reproduced by calculations of the energy landscape based on a macrospin model.įIG. Our results indicate that both Δ and V sw decrease with the increase of H in, with a dominant linear dependence. We then apply the above method combined with switching experiments to reveal the effect of in-plane magnetic fields on the energy landscape and related MTJs parameters. We first provide a method for measuring the voltage-dependent energy barrier height E b(V ), and gain insight into the energy landscape. In this Letter, we investigate the dependence of thermal stability and switching voltage on in-plane magnetic fields (H in). Ohno, IEEE Transactions on Magnetics (50), 1 (2014). Recently, the effect of in-plane magnetic field on the period of the magnetization precession was studied in p-MTJs. The modification of the energy landscape affects the relevant parameters of the MTJs, including: (1) the thermal stability (Δ = E b/k BT, where E b denotes the energy barrier that separates the two magnetization states, k B is the Boltzmann constant, and T is the temperature), which characterizes the ability of the magnetization states to remain stable against thermal fluctuations, (2) the switching voltage (V sw), which corresponds to the voltage required to switch between the two magnetization configurations, and (3) the switching time, equal to half the precession period. and hence modifies the energy landscape and switching behavior. applied externally or provided by an in-plane fixed layer) is needed to ensure a single in-plane precessional axis, 9–11 9. In practical situations however, an in-plane magnetic field (e.g. The magnetization switching is achieved by timing of the pulse duration.
THE PLANE EFFECT SWITCH FREE
During the voltage pulse application, the two stable magnetization states of the free layer disappear in favor of in-plane easy axis and a precessional motion of the magnetization appears. and switching energy down to 6fJ/bit has been achieved in VCMA-controlled CoFeB/MgO magnetic tunnel junctions with perpendicular anisotropy (p-MTJs). Wang, 2012 IEEE International Electron Devices Meeting (2012).
Nanosecond bidirectional magnetization switching by the application of unipolar voltage pulses has been demonstrated, 1–4 1. while employing conventional material combinations of stable MTJs with high tunneling magnetoresistance (TMR) ratios. Ocker, Magnetics, IEEE Transactions on Magnetics (99), 1 (2015). Khalili Amiri, Journal of Physics D: Appl. offering the potential for ultralow switching energy, 5–8 5. Magnetic tunnel junctions (MTJs) exploiting voltage-controlled magnetic anisotropy (VCMA) have attracted interest for use in memory applications, 1–11 1.
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