Parametric oscillator based on nonlinear vortex dynamics in low-resistance magnetic tunnel junctions

Martin, S. Y.; Mestier, N. de; Thirion, C.; Hoarau, Christophe; Conraux, Y.; Baraduc, C.; Diény, B.

doi:10.1103/physrevb.84.144434

Cited by 26 publications

(19 citation statements)

References 23 publications

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“…They are etched as pillars of 300 nm diameter. In a previous paper 4 we have shown that injecting a large dc current through the sample induces the formation of a magnetic vortex in the free layer due to the large Oersted field. At some critical current, spin transfer torque induces gyrotropic motion of the vortex, thus leading to a large rf response.…”

Section: Methodsmentioning

confidence: 99%

“…Its signature is seen in the power spectral density of the junction, that shows a large peak around 400 MHz and up to 10 − 12 harmonics. The dynamical properties of this oscillator were thoroughly studied with respect to synchronization, leading us to deduce it behaves as a parametric oscillator 4 . Here we examine frequency modulation on the same samples, in the same experimental conditions.…”

Section: Methodsmentioning

confidence: 99%

“…Up to now, such studies were devoted only to macrospin oscillators. Here we performed low-noise frequency modulation measurements on a vortex oscillator, based on a magnetic tunnel junction nanopillar in an in-plane field 4 . We also develop an analysis based on modulation theory to treat the whole set of data at once.…”

Section: Introductionmentioning

confidence: 99%

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Tunability versus deviation sensitivity in a nonlinear vortex oscillator

et al. 2013

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Frequency modulation experiments were performed on a spin torque vortex oscillator for a wide range of modulation frequency, up to 10 % of the oscillator frequency. A thorough analysis of the intermodulation products shows that the key parameter that describes these experiments is the deviation sensitivity, which is the dynamical frequency-current dependence. It differs significantly from the oscillator tunability discussed so far in the context of spin-transfer oscillators. The essential difference between these two concepts is related to the response time of the vortex oscillator, driven either in quasi-steady state or in a transient regime.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Tunability versus deviation sensitivity in a nonlinear vortex oscillator

et al. 2013

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“…Recently, so-called parametric synchronization of STNOs [30][31][32][33][34][35], where f RF is about 2f 0 , was demonstrated experimentally. Parametric synchronization offers several advantages over injection locking done at the fundamental frequency.…”

Section: Introductionmentioning

confidence: 99%

Time-domain stability of parametric synchronization in a spin-torque nano-oscillator based on a magnetic tunnel junction

et al. 2017

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We report on time-domain stability of the parametric synchronization in a spin-torque nanooscillator (STNO) based on a magnetic tunnel junction. Time-domain measurements of the instantaneous frequency (fi) of a parametrically synchronized STNO show random short-term unlocking of the STNO signal for low injected radio-frequency (RF) power, which cannot be revealed in time-averaged frequency domain measurements. Macrospin simulations reproduce the experimental results and reveal that the random unlocking during synchronization is driven by thermal fluctuations. We show that by using a high injected RF power, random unlocking of the STNO can be avoided. However, a perfect synchronization characterized by complete suppression of phase noise, so-called phase noise squeezing, can be obtained only at a significantly higher RF power. Our macrospin simulations suggest that a lower temperature and a higher positive ratio of the field-like torque to the spin transfer torque reduce the threshold RF power required for phase noise squeezing under parametric synchronization.

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“…6 At the same time, it is recognised that the linewidth of STOs can be undesirably large, owing to the frequency and phase noise of the auto-oscillations. 15,16,17,18,19,20 This has led to a number of studies of the mutual synchronization of multiple STOs 21,22,23,24,25,26,27,28,13,29,30 and phase-locking of STOs to an injected microwave (RF) current 20,31,32,33,34,35,36 in an attempt to enhance their output power and phase stability.…”

Section: Introductionmentioning

confidence: 99%

Superharmonic injection locking of nanocontact spin-torque vortex oscillators

et al. 2016

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Super-harmonic injection locking of single nano-contact (NC) spin-torque vortex oscillators (STVOs) subject to a small microwave current has been explored. Frequency locking was observed up to the fourth harmonic of the STVO fundamental frequency f0 in microwave magneto-electronic measurements. The large frequency tunability of the STVO with respect to f0 allowed the device to be locked to multiple sub-harmonics of the microwave frequency fRF, or to the same sub-harmonic over a wide range of fRF by tuning the DC current. In general, analysis of the locking range, linewidth, and amplitude showed that the locking efficiency decreased as the harmonic number increased, as expected for harmonic synchronization of a non-linear oscillator. Time-resolved scanning Kerr microscopy (TRSKM) revealed significant differences in the spatial character of the magnetization dynamics of states locked to the fundamental and harmonic frequencies, suggesting significant differences in the core trajectories within the same device. Super-harmonic injection locking of a NC-STVO may open up possibilities for devices such as nanoscale frequency dividers, while differences in the core trajectory may allow mutual synchronisation to be achieved in multi-oscillator networks by tuning the spatial character of the dynamics within shared magnetic layers.

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Parametric oscillator based on nonlinear vortex dynamics in low-resistance magnetic tunnel junctions

Abstract: International audienc

Cited by 26 publications

References 23 publications

Tunability versus deviation sensitivity in a nonlinear vortex oscillator

Tunability versus deviation sensitivity in a nonlinear vortex oscillator

Time-domain stability of parametric synchronization in a spin-torque nano-oscillator based on a magnetic tunnel junction

Superharmonic injection locking of nanocontact spin-torque vortex oscillators

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