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M. Ahlberg
University of Gothenburg
Corresponding Author
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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.
Keywords
spintronics, magnetic droplets, magnetic devices
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Figure 4
There is NO Competing Interest.
This is a list of supplementary files associated with this preprint. Click to download.
- FigureSupMat.jpg
Figure S1: Supplementary Fig.1. A zoom-in of the phase diagram in Fig. 3(a) of the main text. The color code represents the different states: droplet (green), bubble (gray) and antiparallel (red). A droplet is nucleated at high currents and fields. Below a certain positive field (Hbalance) the droplet is stabilized as a static bubble due to magnetostatic effects2. The bubble is pinned below the nanocontact until the negative field is high enough to let the bubble domain expand throughout the film at Hpinning. At low currents the magnetic switching is only governed by the coercive field (Hc) of the free layer.
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This preprint is under consideration at a Nature Portfolio Journal. A preprint is a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
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Article
M. Ahlberg
University of Gothenburg
Corresponding Author
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
Peer Review Timeline
CURRENT STATUS: Under Review
Version 1
Posted 17 May, 2021
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
License:
This work is licensed under a CC BY 4.0 License. Read Full License
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.
Figure 1
Figure 2
Figure 3
Figure 4
There is NO Competing Interest.
This is a list of supplementary files associated with this preprint. Click to download.
- FigureSupMat.jpg
Figure S1: Supplementary Fig.1. A zoom-in of the phase diagram in Fig. 3(a) of the main text. The color code represents the different states: droplet (green), bubble (gray) and antiparallel (red). A droplet is nucleated at high currents and fields. Below a certain positive field (Hbalance) the droplet is stabilized as a static bubble due to magnetostatic effects2. The bubble is pinned below the nanocontact until the negative field is high enough to let the bubble domain expand throughout the film at Hpinning. At low currents the magnetic switching is only governed by the coercive field (Hc) of the free layer.
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