Dependence of the colored frequency noise in spin torque oscillators on current and magnetic field

Eklund, Anders; Bonetti, Stefano; Sani, Sohrab R.; Mohseni, Seyed Majid; Persson, Johan; Chung, Sunjae; Banuazizi, Seyed Amir Hossein; Iacocca, Ezio; Östling, Mikael; Åkerman, Johan; Malm, B. Gunnar

doi:10.1063/1.4867257

Cited by 29 publications

(28 citation statements)

References 28 publications

(30 reference statements)

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“…(2)(3), cannot implicitly be specified as different physical processes are potential origins. This includes intrinsic phenomena such as fluctuations in the magnetic texture 28,29,49 , the impact of defects and/or inhomogeneities in the magnetic layers or the tunnel barrier in particular due to the fabrication process 33 . Even external fluctuations of the driving dc current or the applied magnetic field can play a role.…”

Section: Results -Noise In Stvosmentioning

confidence: 99%

“…In particular, we avoid any perturbing effects of mode crossing (as in Ref. 33 ) or more complex dynamical behaviour in the regime of very large excitation. Indeed beyond the stable gyrotropic mode (mode crossing, energy transfer into other subordinate modes), under specific current and field conditions, the occurrence of Random Telegraph Noise (RTN) at characteristic frequencies of up to 10 kHz can be observed.…”

Section: Methodsmentioning

confidence: 99%

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Low offset frequency 1/f flicker noise in spin-torque vortex oscillators

et al. 2019

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Low frequency noise close to the carrier remains little explored in spin torque nano oscillators. However, it is crucial to investigate as it limits the oscillator's frequency stability. This work addresses the low offset frequency flicker noise of a TMR-based spin-torque vortex oscillator in the regime of large amplitude steady oscillations. We first phenomenologically expand the nonlinear auto-oscillator theory aiming to reveal the properties of this noise. We then present a thorough experimental study of the oscillator's 1/f flicker noise and discuss the results based on the theoretical predictions. Hereby, we connect the oscillator's nonlinear dynamics with the concept of flicker noise and furthermore refer to the influence of a standard 1/f noise description based on the Hooge formula, taking into account the non-constant magnetic oscillation volume, which contributes to the magnetoresistance. arXiv:1906.10190v2 [cond-mat.mes-hall]

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Section: Results -Noise In Stvosmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Low offset frequency 1/f flicker noise in spin-torque vortex oscillators

et al. 2019

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“…As STT can act as negative spin wave damping, it can realize magnetic systems where spin waves, instead of being damped out, can grow exponentially in amplitude, until additional non-linear damping balances the magnetodynamics and a steady state of intense spin wave generation is realized [4][5][6]. This auto-oscillatory state is the basis for spin torque nanooscillators (STNOs) with promise for use as ultra-broadband, rapidly modulated, truly nanoscopic, and RF CMOS compatible microwave signal generators [5][6][7][8][9][10][11][12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Magnetic droplet solitons in orthogonal spin valves

Chung

Mohseni

Eklund

et al. 2015

Low Temperature Physics

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We review the recent experimental advancements in the realization and understanding of magnetic droplet solitons generated by spin transfer torque in orthogonal nanocontact based spin torque nanooscillators (STNOs) fabricated on extended spin valves and spin valve nanowires. The magnetic droplets are detected and studied using the STNO microwave signal and its resistance, the latter both quasistatically and time-resolved. The droplet nucleation current is found to have a minimum at intermediate magnetic field strengths and the nature of the nucleation changes gradually from a single sharp step well above this field, mode-hopping around the minimum, and continuous at low fields. The mode-hopping and continuous transitions are ascribed to droplet drift instability and re-nucleation at different time scales, which is corroborated by time-resolved measurements. We argue that the use of tilted anisotropy fixed layers could reduce the nucleation current further, move the nucleation current minimum to lower fields, and potentially remove the need for an applied magnetic field altogether. Finally, evidence of an edge mode droplet in a nanowire is presented. PACS: 75.30.Ds Spin waves;75.75.-c Magnetic properties of nanostructures.

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“…The GMR STO used in this work is nanocontact-based and similar to those in [10,22]. Thus, the biasing conditions, including the applied DC current, the magnitude and angle of the magnetic field, for driving GMR STOs as well as tuning their operating frequencies, are also similar.…”

Section: System Architecturementioning

confidence: 96%