Current-Induced Spin-Wave Excitations in a Single Ferromagnetic Layer

Ji, Yi; Chien, C. L.; Stiles, Mark D.

doi:10.1103/physrevlett.90.106601

Cited by 123 publications

(148 citation statements)

References 28 publications

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“…Such variation can give instabilities at a single interface, a possible explanation for spin transfer effects seen in point contact experiments [38]. Brataas et al [39] reported a theoretical study on the mode dependence of current-induced magnetic excitations in spin valves, and found agreement with the experimental results of Ref.…”

Section: Previous Studies On Non-local Spin Transfer Torque Due To Lasupporting

confidence: 72%

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Self-consistent calculation of spin transport and magnetization dynamics

et al. 2013

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A spin-polarized current transfers its spin-angular momentum to a local magnetization, exciting various types of current-induced magnetization dynamics. So far, most studies in this field have focused on the direct effect of spin transport on magnetization dynamics, but ignored the feedback from the magnetization dynamics to the spin transport and back to the magnetization dynamics. Although the feedback is usually weak, there are situations when it can play an important role in the dynamics. In such situations, simultaneous, self-consistent calculations of the magnetization dynamics and the spin transport can accurately describe the feedback. This review describes in detail the feedback mechanisms, and presents recent progress in self-consistent calculations of the coupled dynamics. We pay special attention to three representative examples, where the feedback generates non-local effective interactions for the magnetization after the spin accumulation has been integrated out. Possibly the most dramatic feedback example is the dynamic instability in magnetic nanopillars with a single magnetic layer. This instability does not occur without non-local feedback. We demonstrate that full self-consistent calculations generate simulation results in much better agreement with experiments than previous calculations that addressed the feedback effect approximately.The next example is for more typical spin valve nanopillars. Although the effect of feedback is less dramatic because even without feedback the current can make stationary states unstable and induce magnetization oscillation, the feedback can still have important consequences. For instance, we show that the feedback can reduce the linewidth of oscillations, in agreement with experimental observations. A key aspect of this reduction is the suppression of the excitation of short wave length spin waves by the non-local feedback.Finally, we consider nonadiabatic electron transport in narrow domain walls. The non-local feedback in these systems leads to a significant renormalization of the effective nonadiabatic 3 spin transfer torque. These examples show that the self-consistent treatment of spin transport and magnetization dynamics is important for understanding the physics of the coupled dynamics and for providing a bridge between the ongoing research fields of current-induced magnetization dynamics and the newly emerging fields of magnetization-dynamics-induced generation of charge and spin currents.

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Section: Previous Studies On Non-local Spin Transfer Torque Due To Lasupporting

confidence: 72%

“…[27], several experimental [36][37][38] and theoretical [28,[39][40][41] studies have been performed to understand the lateral spin diffusion effect. Özyilmaz et al [36] experimentally observed current-induced excitation of a single ferromagnetic layer.…”

Section: Previous Studies On Non-local Spin Transfer Torque Due To Lamentioning

confidence: 99%

Self-consistent calculation of spin transport and magnetization dynamics

et al. 2013

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“…3 it is clear that in the field perpendicular geometry a large plateau in the magnetoresistance is absent. In comparison to point contact experiments [3,6,18] high bias currents in pillar devices appear to lead to a complete magnetization reversal even at high magnetic fields. Our results thus suggest that the peak in dV/dI marks the reversal of the free layer, not the onset of magnetization dynamics.…”

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confidence: 99%

Current-Induced Magnetization Reversal in High Magnetic Fields inCo/Cu/CoNanopillars

et al. 2003

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Current-induced magnetization dynamics in Co/Cu/Co trilayer nanopillars (∼100 nm in diameter) have been studied experimentally at low temperatures for large applied fields perpendicular to the layers. At 4.2 K an abrupt and hysteretic increase in resistance is observed at high current densities for one polarity of the current, comparable to the giant magnetoresistance (GMR) effect observed at low fields. A micromagnetic model, that includes a spin-transfer torque, suggests that the current induces a complete reversal of the thin Co layer to alignment antiparallel to the applied field-that is, to a state of maximum magnetic energy.

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“…When such a compensation occurs, the magnetization either switches to another direction [3,4] or evolves into a steady-state oscillation [5][6][7][8][9]. While the former improves writing operations in magnetic memory devices, the latter enables sustainable ac signal generation from dc inputs, known as spin-torque oscillators [10,11].…”

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confidence: 99%

Terahertz Antiferromagnetic Spin Hall Nano-Oscillator

2016

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We consider the current-induced dynamics of insulating antiferromagnets in a spin Hall geometry. Sufficiently large in-plane currents perpendicular to the Néel order trigger spontaneous oscillations at frequencies between the acoustic and the optical eigenmodes. The direction of the driving current determines the chirality of the excitation. When the current exceeds a threshold, the combined effect of spin pumping and current-induced torques introduces a dynamic feedback that sustains steady-state oscillations with amplitudes controllable via the applied current. The ac voltage output is calculated numerically as a function of the dc current input for different feedback strengths. Our findings open a route towards terahertz antiferromagnetic spin-torque oscillators.

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Current-Induced Spin-Wave Excitations in a Single Ferromagnetic Layer

Cited by 123 publications

References 28 publications

Self-consistent calculation of spin transport and magnetization dynamics

Self-consistent calculation of spin transport and magnetization dynamics

Current-Induced Magnetization Reversal in High Magnetic Fields inCo/Cu/CoNanopillars

Terahertz Antiferromagnetic Spin Hall Nano-Oscillator

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