Phase-locking of multiple magnetic droplets by a microwave magnetic field

Wang, Chengjie; Xiao, Dunhui; Zhou, Yan; Åkerman, Johan; Liu, Yaowen

doi:10.1063/1.4975660

Cited by 13 publications

(10 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We consider that the magnetic dipolar (magnetostatic) interactions affecting the magnetic dynamics of the droplet pair mainly originates from the spins at the part-II region. 26 The dipolar interactions can therefore be calculated by integrating the transient magnetostatic energy due to the magnetic charges generated by the in-plane magnetization. 27 It can be further simplified as: 28 E…”

Section: -mentioning

confidence: 99%

“…One approach to solving this problem can be done by using phase-locking technique through a microwave oscillating magnetic field to synchronize the multiple droplets. 26 However, another study reported that droplets cannot be locked to an external microwave ac current signal. 29 On the other hand, merging multiple droplets into a large droplet may also enhance the output signal because the precession region (part-II) is enlarged.…”

Section: B Merging the Droplet Pairmentioning

confidence: 99%

See 1 more Smart Citation

Merging magnetic droplets by a magnetic field pulse

2018

Self Cite

View full text Add to dashboard Cite

Reliable manipulation of magnetic droplets is of immense importance for their applications in spin torque oscillators. Using micromagnetic simulations, we find that the antiphase precession state, which originates in the dynamic dipolar interaction effect, is a favorable stable state for two magnetic droplets nucleated at two identical nano-contacts. A magnetic field pulse can be used to destroy their stability and merge them into a big droplet. The merging process strongly depends on the pulse width as well as the pulse strength.

show abstract

Section: -mentioning

confidence: 99%

Section: B Merging the Droplet Pairmentioning

confidence: 99%

Merging magnetic droplets by a magnetic field pulse

2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…Due to nonlinearities in the magnetic system, an intrinsic connection of the frequency to the oscillation amplitude occurs [13]. This allows to tune SHOs directly by the strength of the driving spin current and additionally provides an exceptional wide-ranged synchronization to external signals by frequency entrainment [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Injection locking of multiple auto-oscillation modes in a tapered nanowire spin Hall oscillator

Wagner

Smith

Hache

et al. 2018

Sci Rep

View full text Add to dashboard Cite

Spin Hall oscillators (SHO) are promising candidates for the generation, detection and amplification of high frequency signals, that are tunable through a wide range of operating frequencies. They offer to be read out electrically, magnetically and optically in combination with a simple bilayer design. Here, we experimentally study the spatial dependence and spectral properties of auto-oscillations in SHO devices based on Pt(7 nm)/Ni80Fe20(5 nm) tapered nanowires. Using Brillouin light scattering microscopy, we observe two individual self-localized spin-wave bullets that oscillate at two distinct frequencies (5.2 GHz and 5.45 GHz) and are localized at different positions separated by about 750 nm within the SHO. This state of a tapered SHO has been predicted by a Ginzburg-Landau auto-oscillator model, but not yet been directly confirmed experimentally. We demonstrate that the observed bullets can be individually synchronized to external microwave signals, leading to a frequency entrainment, linewidth reduction and increase in oscillation amplitude for the bullet that is selected by the microwave frequency. At the same time, the amplitude of other parasitic modes decreases, which promotes the single-mode operation of the SHO. Finally, the synchronization of the spin-wave bullets is studied as a function of the microwave power. We believe that our findings promote the realization of extended spin Hall oscillators accomodating several distinct spin-wave bullets, that jointly cover an extended range of tunability.

show abstract

“…After the first experimental demonstration of magnetic droplets, reported in STNOs with a PMA Co/Ni free layer and a Co fixed layer 3 , interest in magnetic droplets continues to increase due to its interesting characteristics, such as a highly nonlinear dynamics 2,11,19 , large power emission 3,10,20,21 , and possible applications in microwave-assisted magnetic recording (MAMR) 22,23 and neuromorphic chips as nonlinear oscillators [24][25][26] . Several theoretical 5,11,15,19,[27][28][29][30][31][32][33] and experimental 6-10, 12, 16, 21, 34-38 studies on magnetic droplets have since been presented. and they identify a possible zero-frequency droplet with a topologically trivial magnetic bubble [39][40][41][42][43] .…”

mentioning

confidence: 99%

Freezing and thawing magnetic droplet solitons

Ahlberg

Chung

Jiang

et al. 2021

Preprint

View full text Add to dashboard Cite

Magnetic droplets are non-topological magnetodynamical solitons displaying a wide range of complex dynamic phenomena with potential for microwave signal generation. Bubbles, on the other hand, are internally static cylindrical magnetic domains, stabilized by external fields and magnetostatic interactions. In its original theory, the droplet was described as an imminently collapsing bubble stabilized by spin transfer torque and, in its zero-frequency limit, as equivalent to a bubble. Without nanoscale lateral confinement, pinning, or an external applied field, such a nanobubble is unstable, and should collapse. Here, we show that we can freeze dynamic droplets into static nanobubbles by decreasing the magnetic field. While the bubble has virtually the same resistance as the droplet, all signs of low-frequency microwave noise disappear. The transition is fully reversible and the bubble can be thawed back into a droplet if the magnetic field is increased under current. Whereas the droplet collapses without a sustaining current, the bubble is highly stable and remains intact for days without external drive. Electrical measurements are complemented by direct observation using scanning transmission x-ray microscopy, which corroborates the analysis and confirms that the bubble is stabilized by pinning.

show abstract

Phase-locking of multiple magnetic droplets by a microwave magnetic field

Cited by 13 publications

References 34 publications

Merging magnetic droplets by a magnetic field pulse

Merging magnetic droplets by a magnetic field pulse

Injection locking of multiple auto-oscillation modes in a tapered nanowire spin Hall oscillator

Freezing and thawing magnetic droplet solitons

Contact Info

Product

Resources

About