Phase-locking of magnetic vortices mediated by antivortices

Ruotolo, A.; Cros, Vincent; Georges, B.; Dussaux, A.; Grollier, Julie; Deranlot, C.; Guillemet, R.; Bouzéhouane, K.; Fusil, S.; Fert, A.

doi:10.1038/nnano.2009.143

Cited by 302 publications

(253 citation statements)

References 27 publications

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“…Practical applications of spin torque nano-oscillators (STNOs) require high output power levels and low phase noise 8,9,10 . Several approaches pursuing these goals, such as phase locking of arrays of STNOs 11,12,13,14 and development of STNOs based on magnetic tunnel junctions 15,16,17,18 are active areas of research.…”

Section: Introductionmentioning

confidence: 99%

“…The two-dimensional systems offer the advantage of phase locking of nearby STNOs via interaction by spin waves propagating in the common ferromagnetic free layer 11,12 . The phase locking regime is attractive from the practical point of view because the output power of STNOs increases and their phase noise decreases in this regime 11,12,13 .…”

Section: Introductionmentioning

confidence: 99%

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Micromagnetic simulations of magnetization dynamics in a nanowire induced by a spin-polarized current injected via a point contact

Berkov

Boone

2011

Phys. Rev. B

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We present a detailed numerical analysis of the magnetization auto-oscillations induced in a thin NiFe nanowire by a direct spin polarized current injected via a square-shaped CoFe nanomagnet (a system experimentally studied in C. Boone et al., Phys. Rev. B 79, 140404 (2009)). We demonstrate that all auto-oscillation modes in the nanowire are localized under the nanocontact for magnetic field applied in the plane of the nanowire. This mode localization is induced by a strong stray magnetic field acting on the NiFe nanowire from the CoFe current injector. We find that the auto-oscillation frequency, power and the frequency shift with the current strongly depend on the exchange constant of NiFe. We also find that the auto-oscillation power depends non-monotonically on the CoFe saturation magnetization, and demonstrate that this effect has its origin in resonant excitation of the CoFe eigenmodes by magnetization oscillations in the NiFe nanowire. The calculated dependence of the oscillation frequency on current is in a good agreement with the experiment. However, the agreement between theory and experiment for the oscillation power is unsatisfactory. Finally, we have shown that an auto-oscillatory mode propagating along the nanowire in the system under study is possible when a sufficiently strong out-of-plane field is applied.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Micromagnetic simulations of magnetization dynamics in a nanowire induced by a spin-polarized current injected via a point contact

Berkov

Boone

2011

Phys. Rev. B

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“…Their main drawbacks are their limited output power and high phase noise caused by tiny mode volumes and a strong frequency-power nonlinearity [25][26][27][28] . Although the solution lies in the mutual synchronization of several nanocontacts, this has only been achieved for two highfrequency nanocontact STOs [29][30][31][32][33] and four low-frequency vortex STOs 34 , all fabricated using either low-volume e-beam lithography or atomic force microscopy nano-indentation.…”

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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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“…Magnetic vortices in sub-micron sized dots have gained considerable interests in recent years due to their unique reversal mechanisms, fascinating topological properties, and potential applications in information storage, [1][2][3][4][5][6] spin-torque oscillators, 7,8 magnetic memory and logic devices, 9 and targeted cancer-cell destruction strategies. 10 Vortices are one type of topological defects characterized by an in-plane magnetization with a clockwise (CW) or counter-clockwise (CCW) chirality and a central core with an out-of-plane magnetization (up or down polarity).…”

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confidence: 99%

“…6 Vortex interaction further offers a synchronization route to achieve nanosized spin-torque oscillators for microwave generation. 8,11 Additionally, the dimensional crossover from vortices to domain walls (DWs) 12 leads to the occurrence of vortices in DWs, which influences the DW manipulation by a spin-polarized current. 9 Very recently, halfvortices 13 have been theoretically recognized as another important class of elementary topological defects.…”

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confidence: 99%

Chirality control via double vortices in asymmetric Co dots

et al. 2011

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Reproducible control of the magnetic vortex state in nanomagnets is of critical importance. We report on chirality control by manipulating the size and/or thickness of asymmetric Co dots. Below a critical diameter and/or thickness, chirality control is achieved by the nucleation of single vortex. Interestingly, above these critical dimensions chirality control is realized by the nucleation and subsequent coalescence of two vortices, resulting in a single vortex with the opposite chirality as found in smaller dots. Micromagnetic simulations and magnetic force microscopy highlight the role of edge-bound halfvortices in facilitating the coalescence process.Comment: 15 pages, 4 figure

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Phase-locking of magnetic vortices mediated by antivortices

Cited by 302 publications

References 27 publications

Micromagnetic simulations of magnetization dynamics in a nanowire induced by a spin-polarized current injected via a point contact

Micromagnetic simulations of magnetization dynamics in a nanowire induced by a spin-polarized current injected via a point contact

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

Chirality control via double vortices in asymmetric Co dots

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