Limits for the vortex state spin torque oscillator in magnetic nanopillars: Micromagnetic simulations for a thin free layer

Aranda, G. R.; González, J.; Val, J. J. del; Guslienko, K. Yu.

doi:10.1063/1.3524222

Cited by 15 publications

(11 citation statements)

References 59 publications

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“…Compared with the dynamical scenarios reported by Aranda et al , we do not see the in‐plane magnetization oscillation when the VC is expelled out of the dot. This may be due to the larger thickness of our disk, because a thicker dot corresponds to a larger exciting current, and it will induce a higher Oersted field, which makes the S or C state unstable.…”

Section: Resultscontrasting

confidence: 89%

“…The characteristic mechanism depends on the dot size, for example, the VC are switched by the first type when R ¼ 100 nm, however, the VC is reversed by the second type when R ¼ 200 nm. The Compared with the dynamical scenarios reported by Aranda et al [30], we do not see the in-plane magnetization oscillation when the VC is expelled out of the dot. This may be due to the larger thickness of our disk, because a thicker dot corresponds to a larger exciting current, and it will induce a higher Oersted field, which makes the S or C state unstable.…”

Section: Ii-iii Psupporting

confidence: 73%

“…In regime III p (

J \geq J_{normalp}^{II - III}

), the polarity of VC is switched from p = 1 to −1. The asymmetric switching of VC polarity can be achieved by two types of mechanisms, one is by the VC expelling and subsequent return to the dot with opposite polarity , and the other is by formation and annihilation of a vortex–antivortex pair . The characteristic mechanism depends on the dot size, for example, the VC are switched by the first type when R = 100 nm, however, the VC is reversed by the second type when R = 200 nm.…”

Section: Resultsmentioning

confidence: 99%

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Dynamics of a magnetic vortex driven by an out‐of‐plane spin‐polarized current in a point‐contact geometry with lateral confinement

Liu

et al. 2013

Physica Status Solidi (b)

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We report the dynamical behaviors of a magnetic vortex driven by an out-of-plane spin-polarized current in a point-contact geometry using a micromagnetic simulation method. Polarity, chirality, and polarity plus chirality-switching diagrams are presented corresponding to different current states. Besides vortex core gyrotropic motion, polarity switching, chirality switching, and polarity plus chirality switching, we also observe non-switching and partial switching behaviors in some cases. Investigations of these switching behaviors find that polarity is switched by nucleation and annihilation of the vortex-antivortex pair for the polarity-switching only regime, and chirality reversal is realized by moving, nucleation, and annihilation of vortices in the disk for lower current density, but by propagating of spin waves for higher current density. Moreover, the reversal of chirality is always accompanied by polarity switching, and the accompanied polarity switching for the higher current density case is realized by the expansion and compression of the vortex core, not the traditional vortexantivortex pair-mediated mechanism.

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Section: Resultscontrasting

confidence: 89%

Section: Ii-iii Psupporting

confidence: 73%

“…In regime III p (

J \geq J_{normalp}^{II - III}

Section: Resultsmentioning

confidence: 99%

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Dynamics of a magnetic vortex driven by an out‐of‐plane spin‐polarized current in a point‐contact geometry with lateral confinement

Liu

et al. 2013

Physica Status Solidi (b)

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“…at the nanoscale), (ii) broad and steady working frequency. Currently, STNOs are roughly divided into two kinds: (a) precessional motion of uniform magnetization [29] and (b) magnetic vortex oscillations [30][31][32][33][34][35][36]. Vortex-based STNOs could present a high output power [37], and a narrow spectral linewidth [32].…”

mentioning

confidence: 99%

Current-induced magnetic skyrmions oscillator

et al. 2015

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Spin transfer nano-oscillators (STNOs) are nanoscale devices which are promising candidates for onchip microwave signal sources. For application purposes, they are expected to be nano-sized, to have broad working frequency, narrow spectral linewidth, high output power and low power consumption. In this paper, we demonstrate by micromagnetic simulation that magnetic skyrmions, topologically stable nanoscale magnetization configurations, can be excited into oscillation by a spin-polarized current. Thus, we propose a new kind of STNO using magnetic skyrmions. It is found that the working frequency of this oscillator can range from nearly 0 Hz to gigahertz. The linewidth can be smaller than 1 MHz. Furthermore, this device can work at a current density magnitude as small as 10 8 A m −2 , and it is also expected to improve the output power. Our studies may contribute to the development of skyrmion-based microwave generators. IntroductionSkyrmions are topologically protected objects with particle-like properties that play an important role in many different contexts, such as liquid crystals [1], quantum Hall magnets [2], Bose-Einstein condensates [3], etc. Recently, with the development of observation technology, particularly in the domain of neutron scattering [4], spin-polarized scanning tunneling microscopy (STM) [5], Lorentz force microscopy [6-8], and electron holography [9], skyrmions have been observed in bulk ferromagnetic crystals, thin films and nanowires. The spin texture of magnetic skyrmions is a stable configuration that, in most systems, results from a balance between the ferromagnetic exchange coupling, the Zeeman energy from the applied field and the chiral interaction, known as the Dzyaloshinskii-Moriya interaction (DMI) [10][11][12]. The DMI is induced because of the lack of, or breaking of, inversion symmetry in the magnetic structure, either due to the non-centrosymmetric crystal lattice or to the interfaces between different materials [8].Magnetic skyrmions were originally discovered in bulk ferromagnets lacking inversion symmetry, such as MnSi [13], FeGe [7,14], Fe 0.5 Co 0.5 Si [15] and other B20 transition metal compounds [16]. Then they were observed in thin films and nanowires of similar materials [9,17,18], and recently, in the multiferroic insulator Cu 2 OSeO 3 [19]. In addition, a more stable two-dimensional skyrmion crystal has been created artificially by nanopatterning [20] and a spontaneous skyrmion ground state has been created in Co/Ru/Co multilayer nanodisks without the DMI (the competition of the exchange energy, demagnetization energy and uniaxial anisotropy energy acts similar to the DMI) by a numerical approach [21]. Meanwhile, an effective method was reported to nucleate or annihilate isolated skyrmions experimentally by using STM at one monolayer of Fe grown in Ir(111) [22].It was recently realized that the magnetic skyrmions not only have mathematical beauty but can also be used as spintronic devices. Recent research has demonstrated that magnetic skyrmions have great potentia...

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“…Alternatively, the polarity reversal also can be realized when VC is expelled out of the dot, i.e. a41 [19,20]. These two criterions determine the value of the second critical current density J 2 .…”

Section: Introductionmentioning

confidence: 98%

Steady vortex gyrotropic motion driven by an out-of-plane spin-polarized current in a confined nanocontact structure

Liu

et al. 2015

Solid State Communications

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Limits for the vortex state spin torque oscillator in magnetic nanopillars: Micromagnetic simulations for a thin free layer

Cited by 15 publications

References 59 publications

Dynamics of a magnetic vortex driven by an out‐of‐plane spin‐polarized current in a point‐contact geometry with lateral confinement

Dynamics of a magnetic vortex driven by an out‐of‐plane spin‐polarized current in a point‐contact geometry with lateral confinement

Current-induced magnetic skyrmions oscillator

Steady vortex gyrotropic motion driven by an out-of-plane spin-polarized current in a confined nanocontact structure

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