Reduction of back switching by large damping ferromagnetic material

Taniguchi, Tadatsugu; Shiokawa, Y.; Sasaki, T.

doi:10.35848/1882-0786/abc6eb

Cited by 3 publications

(2 citation statements)

References 36 publications

(83 reference statements)

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“…We notice that the auto-oscillation is excited when β is positive. In fact, auto-oscillations have not been observed in this geometry when the field-like torque is absent [24,45,46] or β is negative [29]. This argument is also confirmed from the critical-current formula to excite the auto-oscillation shown in supplementary material, where the critical current is inversely proportional to √ β, and therefore, becomes finite only for a finite β.…”

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confidence: 71%

Out-of-plane magnetization oscillation in spin Hall device assisted by field-like torque

Taniguchi

2021

Preprint

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An excitation of a large-amplitude out-of-plane magnetization oscillation in a ferromagnet by the spin Hall effect is of great interest for practical applications such as microwave generator and neuromorphic computing. However, both experimental and theoretical works have revealed that only small-amplitude oscillation around an in-plane easy axis can be excited via the spin Hall effect. Here, we propose that an out-of-plane oscillation can be excited due to an assistance of field-like torque. We focus on an in-plane magnetized ferromagnet with an easy axis parallel to current direction. We notice that the field-like torque with an appropriate sign provides an additional field modifying the dynamic trajectory of the magnetization and drives the auto-oscillation. The condition on the sign of the field-like torque is satisfied for typical nonmagnet used in spin Hall devices such as tungsten.

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supporting

confidence: 71%

Out-of-plane magnetization oscillation in spin Hall device assisted by field-like torque

Taniguchi

2021

Preprint

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“…For a pulse shut off at 4.8 ns, when the average m z exactly passes the x-axis, the magnetization goes through a period of oscillation around the hard axis in the x-y plane and finally relaxes to the other side, as labeled by the red line in figure 4(a). This anomalous phenomenon, which might be attributed to relatively weak anisotropy field, implies the possible risk of back switching, as mentioned by the researchers [57,58], and thus for clarity, the switching time is regarded as the time that the average m z reaches −0.9. For a pulse width longer than 5 ns, the magnetization relaxes to the other side after the pulse shuts off and the switching time is shortened along with the pulse width increasing.…”

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confidence: 99%

L-shaped electrode design for high-density spin–orbit torque magnetic random access memory with perpendicular shape anisotropy

Chi

Shi²,

Li³

et al. 2021

J. Phys. D: Appl. Phys.

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Magnetic tunneling junctions with strong perpendicular shape anisotropy attract attention due to their high-density magnetic random access memory. As thermal stability increases, the power consumption also increases. To solve this problem, devices are made to be driven by spin–orbit torque (SOT) instead of spin-transfer torque. However, the assisting field needed for deterministic switching is a major obstacle for SOT devices. In this work, we demonstrate an L-shaped electrode structure attached to the magnetic recording layer to induce a composite SOT, achieving high-speed and field-free magnetization switching. Meanwhile, a comparative study between L-shaped and sidewall electrode structure demonstrates that the L-shaped structure leads to fast and low-power switching. Finally, the switching characteristic at various current densities and spin Hall angles is studied and it turns out that to achieve high-speed reversal, the current density and the spin Hall angle need to be optimized, which might be attributed to strong in-plane effective field component disturbance. The novel L-shaped structure is feasible for high-speed, low-power and deterministic switching and has great potential in spintronic applications.

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Out-of-plane magnetization oscillation in spin Hall device assisted by field-like torque

Taniguchi

2021

Applied Physics Letters

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An excitation of a large-amplitude out-of-plane magnetization oscillation in a ferromagnet by the spin Hall effect is of great interest for practical applications such as microwave generators and neuromorphic computing. However, both experimental and theoretical works have revealed that only small-amplitude oscillation around an in-plane easy axis can be excited via the spin Hall effect. Here, we propose that an out-of-plane oscillation can be excited due to an assistance of field-like torque. We focus on an in-plane magnetized ferromagnet with an easy axis parallel to the current direction. We notice that the field-like torque with an appropriate sign provides an additional field, modifying the dynamic trajectory of the magnetization, and drives the auto-oscillation. The condition on the sign of the field-like torque is satisfied for a typical nonmagnet used in spin Hall devices such as tungsten.

show abstract

Reduction of back switching by large damping ferromagnetic material

Cited by 3 publications

References 36 publications

Out-of-plane magnetization oscillation in spin Hall device assisted by field-like torque

Out-of-plane magnetization oscillation in spin Hall device assisted by field-like torque

L-shaped electrode design for high-density spin–orbit torque magnetic random access memory with perpendicular shape anisotropy

Out-of-plane magnetization oscillation in spin Hall device assisted by field-like torque

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