Spin torque oscillator models for applications in associative memories

Csaba, G.; Pufall, Matthew R.; Nikonov, Dmitri E.; Bourianoff, George I.; Horváth, András; Roska, Tamás; Porod, Wolfgang

doi:10.1109/cnna.2012.6331474

Cited by 47 publications

(39 citation statements)

References 3 publications

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“…They also have the potential to open new paths towards neuromorphic computing with spin-torque nanooscillators, where inputs are microwave stimuli, and outputs are the different synchronization states of coupled oscillators arrays [34][35][36][37][38] …”

Section: Injection Lockingmentioning

confidence: 99%

Enhancing the injection locking range of spin torque oscillators through mutual coupling

Romera

Talatchian

Lebrun

et al. 2016

Applied Physics Letters

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We investigate how the ability of the vortex oscillation mode of a spin-torque nanooscillator to lock to an external microwave signal is modified when it is coupled to another oscillator. We show experimentally that mutual electrical coupling can lead to locking range enhancements of a factor 1. 64. Furthermore, we analyze the evolution of the locking range as a function of the coupling strength through experiments and numerical simulations. By uncovering the mechanisms at stake in the locking range enhancement, our results will be useful for designing spin-torque nano-oscillators arrays with high sensitivities to external microwave stimuli.Spin-torque nano-oscillators (STNOs) are promising candidates for the next generation of multifunctional spintronic nano-devices [1] such as efficient integrated microwave generators [2] and detectors [3,4]. One of their characteristic features compared to other auto-oscillators is their high non-linearity [5]. On one hand, this high nonlinearity translates into one of their most attractive properties: their ability to easily adapt their frequencies to external stimuli. On the other hand, by increasing their sensitivity to noise, it has the undesirable effect of broadening the spectral linewidth. In the last few years, many efforts have been made to improve the spectral purity of spintorque oscillators, a crucial step towards most applications. From these studies, a promising approach consists in the synchronization of the oscillators to an external microwave source [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] (injection locking), or to other oscillators [21][22][23][24][25][26][27] (mutual synchronization). In both cases, a crucial parameter to optimize for applications is the locking range, which should be as large as possible. A first way to increase the locking range is to work in regimes where the oscillator's nonlinearity is the largest. However, as mentioned earlier, this comes at the detriment of spectral purity. In the case of injection locking, another possibility is to increase the power of the external signal, but this is limited by the breakdown voltage of the tunnel barrier of the device and results in an increase of power consumption. Therefore, finding alternative paths to enhance the locking range is an important step towards designing next generation's magnetic microwave devices.In this manuscript we combine experimental results with numerical simulations to show that the injection locking range of a spin-torque oscillator can be enhanced by coupling it to another spintorque oscillator. Furthermore, it is shown that the locking range can be tuned by changing the mutual coupling strength between oscillators. (7) is the free layer and numbers represent thickness in nanometers. Samples were grown by sputterdeposition and patterned down to the bottom electrode into circular nanopillars with a diameter of 200 nm. The nano-pillars exhibit a TMR of 64% and a resistance-area product of RA~1 Ω.μm 2 . With this combination of materials and geometry, th...

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Section: Injection Lockingmentioning

confidence: 99%

Enhancing the injection locking range of spin torque oscillators through mutual coupling

Romera

Talatchian

Lebrun

et al. 2016

Applied Physics Letters

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“…While we visit the phase shift key technique, most of the STNO work relies on frequency shift key. Simulation results in effectively identifying patterns [91,46]. Studies also suggests that frequencies are better optimized through a system of STNO over phase [46].…”

Section: Introductionmentioning

confidence: 92%

“…The spintronics research has already established various flavors of alternate non Von-Neumann problem mapping like neuromorphic [157,85,134], and non-Boolean computing with oscillators [47,48]. In general, coupled oscillators have shown to solve associative processes [122,122,167,152].…”

Section: Introductionmentioning

confidence: 99%

Non-Boolean Computing with Spintronic Devices

A.¹,

Bhanja²

2018

FNT in Electronic Design Automation

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“…A possible solution to these issues could be the synchronization of a few STNOs [6,19,21,22,26,28]. Synchronization among multiple auto-oscillators can also be useful in the framework of developing associative memories architectures [29][30][31][32]. Previous studies reported on synchronization of STNOs interacting with others via spin waves [25,26,33], exchange coupling [6], electric currents [3,28,34], noisy current injection [19], or via magnetodipolar interaction [21,22,[35][36][37][38][39][40][41].…”

Section: Introductionmentioning

confidence: 97%

Optimizing magnetodipolar interactions for synchronizing vortex based spin-torque nano-oscillators

et al. 2015

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We report on a theoretical study of the magnetodipolar coupling and synchronization between two vortex-based spin-torque nano-oscillators (STVOs). In this work we study the dependence of the coupling efficiency on the relative magnetization parameters of the vortices in the system. This study is performed in order to propose an optimized configuration of the vortices for synchronizing STVOs. For this purpose, we combine micromagnetic simulations, the Thiele equation approach, and the analytical macrodipole approximation model to identify the optimized configuration for achieving phase-locking between neighboring oscillators. Notably, we compare vortices configurations with parallel (P) core polarities and with opposite (AP) core polarities. We demonstrate that the AP core configuration exhibits a coupling strength about three times higher than in the P core configuration.

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Spin torque oscillator models for applications in associative memories

Cited by 47 publications

References 3 publications

Enhancing the injection locking range of spin torque oscillators through mutual coupling

Enhancing the injection locking range of spin torque oscillators through mutual coupling

Non-Boolean Computing with Spintronic Devices

Optimizing magnetodipolar interactions for synchronizing vortex based spin-torque nano-oscillators

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