Synchronization of spin-transfer oscillators driven by stimulated microwave currents

Grollier, Julie; Boulle, Olivier; Cros, Vincent; Fert, A.

doi:10.1109/intmag.2006.375846

Cited by 19 publications

(28 citation statements)

References 26 publications

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“…It is possible that the simulations might be improved by including recently-proposed mechanisms whereby different regions of a nanomagnet interact through feedback mediated by the current. [25][26][27][28] Above T ≈ 120 K, the measured linewidths (Fig. 2) increase with T much more rapidly than the approximate T 1/2 dependence predicted by the macrospin LLG model.…”

Section: Data and Analysismentioning

confidence: 78%

Mechanisms limiting the coherence time of spontaneous magnetic oscillations driven by dc spin-polarized currents

et al. 2005

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The spin-transfer torque from a DC spin-polarized current can generate highly-coherent magnetic precession in nanoscale magnetic-multilayer devices. By measuring linewidths of spectra from the resulting resistance oscillations, we argue that the coherence time can be limited at low temperature by thermal deflections about the equilibrium magnetic trajectory, and at high temperature by thermally-activated transitions between dynamical modes. Surprisingly, the coherence time can be longer than predicted by simple macrospin simulations.

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Section: Data and Analysismentioning

confidence: 78%

Mechanisms limiting the coherence time of spontaneous magnetic oscillations driven by dc spin-polarized currents

et al. 2005

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“…Further such studies are also important to understand the complex non-linear dynamics of an auto-oscillator and its possible applications to neuromorphic computing [11][12][13]. Injection locking of spin-transfer nano-oscillator (STNO) [14][15][16][17][18][19][20][21][22][23] has been the subject of many experimental and theoretical investigations with the same motivation. SFNO is not limited to the feedback from Oersted magnetic field, but can be even realized from spin current generated by using inverse Spin-Hall effect [24][25].…”

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confidence: 99%

Integer, Fractional, and Sideband Injection Locking of a Spintronic Feedback Nano-Oscillator to a Microwave Signal

et al. 2017

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In this article we demonstrate the injection locking of recently demonstrated spintronic feedback nano oscillator to microwave magnetic fields at integers (n=1, 2, 3) as well fractional multiples (f=1/2, 3/2 and 5/2) of its auto oscillation frequency. Feedback oscillators have delay as a new "degree of freedom" which is absent for spin-transfer torque based oscillators, which gives rise to side peaks along with a main peak. We show that it is also possible to lock the oscillator on its side band peaks, which opens a new avenue to phase locked oscillators with large frequency differences. We observe that for low driving fields, sideband locking improves the quality factor of the main peak, whereas for higher driving fields the main peak is suppressed. Further, measurements at two field angles provide some insight into the role of symmetry of oscillation orbit in determining the fractional locking.Nano-oscillators based on the phenomenon of spin-transfer torque (STT) [1][2][3][4][5][6][7] have been the subject of considerable research due to their potential applications in microwave communication devices as well as due to the rich physics involved in their operation. Recently our group demonstrated a spintronic feedback nano-oscillator (SFNO) [8,9] based on the tunneling magnetoresistance (TMR) effect and works without STT. The working principle of SFNO is as follows: SFNO comprises a magnetic tunnel junction (MTJ) nano-pillar connected to a waveguide on top of it. Such a system, when powered by dc current can amplify rf signals: Rf current passing through the waveguide excites the magnetization of the free layer via oscillating Oersted magnetic field, and the dc current passing through MTJ converts the oscillations of magnetization into ac voltage via tunneling magneto-resistance (TMR) effect. Above a certain dc current level, the input signal is amplified. Thus the free layer of MTJ apart from being a resonator can also work as an amplifier. If we connect a feedback path from MTJ to the waveguide, the system works as an oscillator.It was demonstrated that SFNO [9] can exhibit very large quality factors exceeding 10,000. However, to obtain large output power, it is necessary to connect many oscillators together. If many oscillators can be synchronized, i.e. they oscillate with the same frequency and phase [10], we can get larger power output. We therefore studied the injection locking of a single SFNO to a microwave source, which acts as the second oscillator. Further such studies are also important to understand the complex non-linear dynamics of an auto-oscillator and its possible applications to neuromorphic computing [11][12][13]. Injection locking of spin-transfer nano-oscillator (STNO) [14][15][16][17][18][19][20][21][22][23] has been the subject of many experimental and theoretical investigations with the same 2 motivation. SFNO is not limited to the feedback from Oersted magnetic field, but can be even realized from spin current generated by using inverse . Even interfacial Rashba coupling can be used as ...

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“…A N excitation of a mutually coupled motion of the magnetizations in nanostructured ferromagnets, such as synchronization between spin torque oscillators (STOs) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15], has attracted much attention from the viewpoints of both fundamental physics and practical applications such as phased arrays and brain-inspired computing [16,17]. The mechanism of the synchronization in the previous works was based on the electric and/or magnetic interactions among STOs, such as spin wave propagation, current injection, microwave application, and dipole interaction.…”

Section: Introductionmentioning

confidence: 99%

Coupled Dynamics of Magnetizations in Spin-Hall Oscillators via Spin-Current Injection

Taniguchi

2019

IEEE Trans. Magn.

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An array of spin torque oscillators (STOs) for practical applications such as pattern recognition was recently proposed, where several STOs are connected by a common nonmagnet. In this structure, in addition to the electric and/or magnetic interactions proposed in previous works, the STOs are spontaneously coupled to each other through the nonmagnetic connector, due to the injection of spin current. Solving the Landau-Lifshitz-Gilbert equation numerically for such system consisting of three STOs driven by the spin Hall effect, it is found that both in-phase and antiphase synchronization of the STOs can be achieved by adjusting the current density and appropriate distance between the oscillators.

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Synchronization of spin-transfer oscillators driven by stimulated microwave currents

Cited by 19 publications

References 26 publications

Mechanisms limiting the coherence time of spontaneous magnetic oscillations driven by dc spin-polarized currents

Mechanisms limiting the coherence time of spontaneous magnetic oscillations driven by dc spin-polarized currents

Integer, Fractional, and Sideband Injection Locking of a Spintronic Feedback Nano-Oscillator to a Microwave Signal

Coupled Dynamics of Magnetizations in Spin-Hall Oscillators via Spin-Current Injection

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