Spin Torque–Generated Magnetic Droplet Solitons

Mohseni, Seyed Majid; Sani, Sohrab R.; Persson, Johan; Nguyễn, Thị Ngọc Anh; Chung, Sunjae; Pogoryelov, Yevgen; Muduli, P. K.; Iacocca, Ezio; Eklund, Anders; Dumas, Randy K.; Bonetti, Stefano; Deac, A.; Hoefer, Mark; Åkerman, Johan

doi:10.1126/science.1230155

Cited by 261 publications

(298 citation statements)

References 31 publications

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“…Depending on the geometry and magnetic properties of the free layer, propagating spin waves (SWs) [5][6][7] , solitonic modes [8][9][10][11] , vortex gyration 12,13 , and magnetic dissipative droplets [14][15][16][17] have been observed. STOs can also be used to generate SWs in physically extended thin films, which is of particular interest for future magnonic applications 18,19 .…”

Section: Introductionmentioning

confidence: 99%

Mode-coupling mechanisms in nanocontact spin-torque oscillators

et al. 2015

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Spin torque oscillators (STOs) are devices that allow for the excitation of a variety of magnetodynamical modes at the nanoscale. Depending on both external conditions and intrinsic magnetic properties, STOs can exhibit regimes of mode-hopping and even mode coexistence. Whereas modehopping has been extensively studied in STOs patterned as nanopillars, coexistence has been only recently observed for localized modes in nanocontact STOs (NC-STOs) where the current is confined to flow through a NC fabricated on an extended pseudo spin valve. By means of electrical characterization and a multi-mode STO theory, we investigate the physical origin of the mode coupling mechanisms favoring coexistence. Two coupling mechanisms are identified: (i) magnon mediated scattering and (ii) inter-mode interactions. These mechanisms can be physically disentangled by fabricating devices where the NCs have an elliptical cross-section. The generation power and linewidth from such devices are found to be in good qualitative agreement with the theoretical predictions, as well as provide evidence of the dominant mode coupling mechanisms.

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Section: Introductionmentioning

confidence: 99%

Mode-coupling mechanisms in nanocontact spin-torque oscillators

et al. 2015

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“…Each nanocontact can sustain several tens of mA current, which gets spin polarized and transfers angular momentum between the two magnetic layers via the so-called spin-transfer torque (STT) effect [35][36][37] . At sufficiently high current densities (B10 8 A cm À 2 ), STT can sustain continuous precession of the local magnetization underneath the nanocontact and also inject high amplitudes of either localized or propagating spin waves (SWs) into the free layer 20,22,23,[38][39][40][41][42][43] .…”

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confidence: 99%

Mutually synchronized bottom-up multi-nanocontact spin–torque oscillators

et al. 2013

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Spin-torque oscillators offer a unique combination of nanosize, ultrafast modulation rates and ultrawide band signal generation from 100 MHz to close to 100 GHz. However, their low output power and large phase noise still limit their applicability to fundamental studies of spin-transfer torque and magnetodynamic phenomena. A possible solution to both problems is the spin-wave-mediated mutual synchronization of multiple spin-torque oscillators through a shared excited ferromagnetic layer. To date, synchronization of high-frequency spin-torque oscillators has only been achieved for two nanocontacts. As fabrication using expensive top-down lithography processes is not readily available to many groups, attempts to synchronize a large number of nanocontacts have been all but abandoned. Here we present an alternative, simple and cost-effective bottom-up method to realize large ensembles of synchronized nanocontact spin-torque oscillators. We demonstrate mutual synchronization of three high-frequency nanocontact spin-torque oscillators and pairwise synchronization in devices with four and five nanocontacts.

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“…1(b), we plot a measured magnetoresistance curve [17,19,20] at a fixed current of 27 mA ramping the perpendicular applied field from high to low field at a fixed temperature of 150 K. This shows first the creation (at 1 T) and then the annihilation of the droplet state (0.4 T). Figure 1(c) shows a measured droplet stability map in magnetic field and current space [21,23] built from magnetoresistance curves measured at different applied current at a fixed temperature of 150 K. The no droplet state is plotted in gray and corresponds to a lower resistance state, whereas the green area represents the droplet state, a higher resistance state.…”

Section: Experiments Detailsmentioning

confidence: 99%

“…Dissipative magnetic droplet solitons (droplets hereafter) are nonlinear confined wave excitations consisting of partially reversed precessing spins that can be created in films with perpendicular magnetic anisotropy (PMA) through the local suppression of the magnetic damping [16]. Droplets have been experimentally created using the STT effect in nanocontacts to PMA films [17][18][19][20][21][22][23], and droplets are a particular case of STToscillators. Recently reported experiments have shown that the stability of these collective excitations is limited by the appearance of drift instabilities, which were attributed to the disorderlocal variations of the effective magnetic field [21,24].…”

Section: Introductionmentioning

confidence: 99%

Effect of Temperature on Magnetic Solitons Induced by Spin-Transfer Torque

et al. 2017

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Citation: LENDINEZ, S. ... et al, 2017. Effect of temperature on magnetic solitons induced by spin-transfer torque. Physical Review Applied, 7 (5), 054027.Additional Information:• This paper was accepted for publication in the jour- Spin-transfer torques in a nanocontact to an extended magnetic film can create spin waves that condense to form dissipative droplet solitons. Here we report an experimental study of the temperature dependence of the current and applied field thresholds for droplet soliton formation, as well as the nanocontact's electrical characteristics associated with droplet dynamics. Nucleation requires lower current densities at lower temperatures, in contrast to typical spin-transfer-torque-induced switching between static magnetic states. Magnetoresistance and electrical noise measurements (10 MHz-1 GHz) show that droplet solitons become more stable at lower temperature. These results are of fundamental interest in understanding the influence of thermal noise on droplet solitons and have implications for the design of devices using the spin-transfertorque effects to create and control collective spin excitations.

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Spin Torque–Generated Magnetic Droplet Solitons

Cited by 261 publications

References 31 publications

Mode-coupling mechanisms in nanocontact spin-torque oscillators

Mode-coupling mechanisms in nanocontact spin-torque oscillators

Mutually synchronized bottom-up multi-nanocontact spin–torque oscillators

Effect of Temperature on Magnetic Solitons Induced by Spin-Transfer Torque

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