Optimal protocol for spin-orbit torque switching of a perpendicular nanomagnet

Vlasov, S. M.; Kwiatkowski, Grzegorz; Lobanov, I. S.; Uzdin, V. M.; Bessarab, Pavel F.

doi:10.1103/physrevb.105.134404

Cited by 5 publications

(6 citation statements)

References 46 publications

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“…β = − 1/α is a unique case, for which the system is always in the 'P/AP' bistable state when increasing the current (χ). In [37], it has been proved that β = − 1/α is an ideal ratio to realize a minimum energy cost of the perpendicular magnetization switching. Moreover, with β lying in between −1/α and 0, much richer phases come forth, such as the tiled states, 'tilted/AP' and 'P/tilted' bistable states, and the precessional states.…”

Section: Stability Phase Diagrammentioning

confidence: 99%

“…where I 0 is equation (30) for the high-energy oscillation. The low-energy oscillating frequency is obtained by exchanging a − and b + in equation (37).…”

Section: Frequencymentioning

confidence: 99%

“…To corroborate the analytical results, we numerically solve equation (21), as illustrated in figure 6(a), where the dependance of E eff on χ is shown for different β. Combining equation (37) and the relation between E eff and χ, we plot the frequency as a function of χ in figure 6(b). The analysis of figure 6(b) reveals that the frequency decreases with χ in the low-energy region, while increases in the high-energy region.…”

Section: Frequencymentioning

confidence: 99%

“…This is not embodied in the plot due to the singularity in numeric calculations. But, if we take a limit E eff → E sad in equation (37), the frequency approaches zero from both the low-energy and high-energy regions. This means that the precession ceases on the trajectory through the saddle point.…”

Section: Frequencymentioning

confidence: 99%

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Field-free self-oscillation of magnetization enabled by the fieldlike spin-orbit torque

Wang,

Wan

et al. 2023

Phys. Scr.

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Fieldlike spin-orbit torque, which behaves like a torque from a magnetic field, but relies on the current together with the damplike one, was recognized to influence magnetization switching. However, its role on magnetic oscillations remains to be explored. By linear stability analysis and energy averaging technique, we obtain analytic formulas for the stable boundaries of various states. Then, a phase diagram is constructed, which is controlled by the current and a tunable ratio $\beta$ of the fieldlike torque to the dampinglike one. We find that some new stable, bistable and dynamic states come forth. Especially, a bias-field-free self-oscillation emerges for negative $\beta$, which enables the average energy balance between the dampinglike torque and the intrinsic damping. There occur two kinds of oscillations, analogous to the usual in-plane and out-of-plane precessions. If increasing the current, the frequency declines for the former, and subsequently rises for the latter. Varying $\beta$ slightly affects the frequency range, but dramatically alters the adjustable range of current. In addition, the phase diagram indicates that the switching direction reverses with $\beta$ stepping over $- 1/\alpha$ with $\alpha$ being the damping constant, and the switching current decreases with $\vert \beta \vert$ increasing.

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Section: Stability Phase Diagrammentioning

confidence: 99%

“…where I 0 is equation (30) for the high-energy oscillation. The low-energy oscillating frequency is obtained by exchanging a − and b + in equation (37).…”

Section: Frequencymentioning

confidence: 99%

Section: Frequencymentioning

confidence: 99%

Section: Frequencymentioning

confidence: 99%

See 2 more Smart Citations

Field-free self-oscillation of magnetization enabled by the fieldlike spin-orbit torque

Wang,

Wan

et al. 2023

Phys. Scr.

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“…However, the devices show device longevity and reliability issues [23][24][25][26][27][28][29] because of the higher current density requirement. Very recently, the SOT-induced magnetization switching has drawn much attention [30][31][32][33][34][35], however, the SOT-MRAM cell requires three terminal connections to store one binary digit (bit), which increases the bit-cell area and thus reduces the device density [36]. Alternatively, people employ the microwave field with a constant or time-dependent frequency profile to drive magnetization switching at zero temperature [37][38][39][40][41][42][43][44][45][46][47][48][49][50].…”

Section: Introductionmentioning

confidence: 99%

Thermal effect on microwave pulse-driven magnetization switching of Stoner particle

Chowdhury,

Akanda,

Pikul

et al. 2023

Phys. Scr.

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We investigate the cosine-chirped microwave pulse (cosine CMP)-driven magnetization switching of a nanoparticle or stoner particle at a finite temperature in the framework of the stochastic Landau–Lifshitz-Gilbert equation. Numerical results reveal that the ultrafast and efficient magnetization switching is robust even at room temperature, and hence we estimate the maximal temperature at which the magnetization switching is still valid. The maximal temperature increases with the enlargement (by increasing cross-sectional area) of the nanoparticle/stoner particle volume to a certain value, and afterward, the maximal temperature decreases with the further increment of the nanoparticle size. Initially, the shape anisotropy (approximated by the easy-plane) coefficient does not become dominant although the stoner particle volume increases, which plays a role in increasing thermal stability (maximal temperature), and later the shape anisotropy field becomes dominant, which opposes the uniaxial anisotropy, i.e., reduces the energy barrier, which reduces the maximal temperature. For smaller volumes, the parameters of cosine CMP show a decreasing trend with temperature. The initial frequency requirement significantly decreases with shape anisotropy. Therefore, these findings might be useful to realize cosine CMP-driven fast and energy-efficient magnetization switching in device applications.

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Impact of inherent energy barrier on spin-orbit torques in magnetic-metal/semimetal heterojunctions

Gao,

Qaiumzadeh,

Troncoso

et al. 2023

Nat Commun

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Spintronic devices are based on heterojunctions of two materials with different magnetic and electronic properties. Although an energy barrier is naturally formed even at the interface of metallic heterojunctions, its impact on spin transport has been overlooked. Here, using diffusive spin Hall currents, we provide evidence that the inherent energy barrier governs the spin transport even in metallic systems. We find a sizable field-like torque, much larger than the damping-like counterpart, in Ni81Fe19/Bi0.1Sb0.9 bilayers. This is a distinct signature of barrier-mediated spin-orbit torques, which is consistent with our theory that predicts a strong modification of the spin mixing conductance induced by the energy barrier. Our results suggest that the spin mixing conductance and the corresponding spin-orbit torques are strongly altered by minimizing the work function difference in the heterostructure. These findings provide a new mechanism to control spin transport and spin torque phenomena by interfacial engineering of metallic heterostructures.

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Optimal protocol for spin-orbit torque switching of a perpendicular nanomagnet

Cited by 5 publications

References 46 publications

Field-free self-oscillation of magnetization enabled by the fieldlike spin-orbit torque

Field-free self-oscillation of magnetization enabled by the fieldlike spin-orbit torque

Thermal effect on microwave pulse-driven magnetization switching of Stoner particle

Impact of inherent energy barrier on spin-orbit torques in magnetic-metal/semimetal heterojunctions

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