Multiple-mode excitation in spin-transfer nanocontacts with dynamic polarizer

Wang, N.; Wang, X. L.; Qin, Wei; Yeung, Sai Ho; Kwok, Dixon T. K.; Wong, Hon Fai; Xue, Quan; Chu, Paul K.; Leung, Chi Wah; Ruotolo, A.

doi:10.1063/1.3600328

Cited by 8 publications

(9 citation statements)

References 14 publications

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“…21,22 Especially, vortices that are coupled vertically via a nonmagnetic interlayer are of interest, [23][24][25][26][27][28][29][30][31][32][33][34] as significant magnetoresistance and spin-torque phenomena may occur. [35][36][37][38][39] The relevant coupling mechanisms for such geometries are the magnetodipolar interaction and, depending on the spacer material and thickness, also interlayer exchange coupling (IEC). [40][41][42][43] As sketched in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…The reports available on interlayer-coupled vortices can be categorized into static investigations 23,24,[26][27][28][29] on the one hand and magnetization dynamics studies using external fields [30][31][32][33][34] or spin-polarized currents [35][36][37][38][39] as excitation sources on the other hand. Many of the approaches used to analyze the system are theoretical, [30][31][32][33]39 whereas the experimental approaches are often based on integral resistance measurements, [35][36][37][38] or rely on information averaged from an ensemble of structures. [26][27][28][29] Only Refs.…”

Section: Introductionmentioning

confidence: 99%

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Interlayer-coupled spin vortex pairs and their response to external magnetic fields

et al. 2012

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We report on the response of multilayer spin textures to static magnetic fields. Coupled magnetic vortex pairs in trilayer elements (ferromagnetic/nonmagnetic/ferromagnetic) are imaged directly by means of layer-selective magnetic x-ray microscopy. We observe two different circulation configurations with parallel and opposing senses of magnetization rotation at remanence. Upon application of a field, all of the vortex pairs investigated react with a displacement of their cores. For purely dipolar coupled pairs, the individual core displacements are similar to those of an isolated single-layer vortex, but also a noticeable effect of the mutual stray fields is detected. Vortex pairs that are linked by an additional interlayer exchange coupling (IEC), which is either ferromagnetic or antiferromagnetic, mainly exhibit a layer-congruent response. We find that, apart from a possible decoupling at higher fields, these strict IEC vortex pairs can be described by a single-layer model with effective material parameters. This result implies the possibility to design multilayer spin structures with arbitrary effective magnetization.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Interlayer-coupled spin vortex pairs and their response to external magnetic fields

et al. 2012

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“…4(d)]. Such a double-frequency mode has been observed in other STNOs [40][41][42][43][44][45][46], and can either result from the hopping between two frequencies, or from the simultaneous emission of two frequencies. Such cases are discussed in more detail in the following section.…”

Section: Frequency Domain Analysismentioning

confidence: 73%

Nanocontact vortex oscillators based on Co$_2$MnGe pseudo-spin valves

Létang,

de Melo,

Guillemard

et al. 2020

Preprint

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We present an experimental study of vortex dynamics in magnetic nanocontacts based on pseudo spin valves comprising the Co 2 MnGe Heusler compound. The films were grown by molecular beam epitaxy, where precise stoichiometry control and tailored stacking order allowed us to define the bottom ferromagnetic layer as the reference layer, with minimal coupling between the free and reference layers. 20-nm diameter nanocontacts were fabricated using a nano-indentation technique, leading to self-sustained gyration of the vortex generated by spin-transfer torques above a certain current threshold. By combining frequency-and time-domain measurements, we show that different types of spin-transfer induced dynamics related to different modes associated to the magnetic vortex configuration can be observed, such as mode hopping, mode coexistence and mode extinction appear in addition to the usual gyration mode.

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“…By using the experimental values of M s 0 μ , d pl , α, and L, and by assuming a spin polarization of P ¼0.5 and a radius of the vortex core r 10 nm core = , we find a theoretical value for I / 4MHz/mA osc ω ∂ ∂ = in the low frequency regime, which matches with the observed slope experimentally of E 3.6 MHz/mA from Eq. (10). The jump in frequency can be calculated theoretically and accounts for a jump of 36 MHz similar to the observed one of E 37 MHz.…”

Section: Influence Of a V-av Pair In The Pl Onto The Oscillating Vortmentioning

confidence: 93%

“…Previous studies [10,11] have suggested that the two ferromagnetic layers of a nanocontacted spin-valve structure may contain a vortex state under certain conditions of the applied magnetic field and injected current. To date, a successful model to explain the new observed dynamics has been lacking.…”

Section: Introductionmentioning

confidence: 99%

Dynamical influence of vortex–antivortex pairs in magnetic vortex oscillators

Otxoa

Petit-Watelot

Manfrini

et al. 2015

Journal of Magnetism and Magnetic Materials

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a b s t r a c tWe study the magnetization dynamics in a nanocontact magnetic vortex oscillators as function of temperature. Low temperature experiments reveal that the dynamics at low and high currents differ qualitatively. At low currents, we excite a temperature independent standard oscillation mode, consisting of a gyrotropic motion of a vortex about the nanocontact in the free layer. Above a critical current, a sudden jump in the frequency is observed, which occurs with a substantial increase of the frequency versus current slope factor. Using micromagnetic simulation and analytical modeling, we associate this new regime to the creation of a vortex-antivortex pair in the pinned layer of the spin valve. This pair gives an additional perpendicular spin torque component that alters the free layer vortex dynamics, which can be quantitatively accounted for by an analytical model.

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Multiple-mode excitation in spin-transfer nanocontacts with dynamic polarizer

Cited by 8 publications

References 14 publications

Interlayer-coupled spin vortex pairs and their response to external magnetic fields

Interlayer-coupled spin vortex pairs and their response to external magnetic fields

Nanocontact vortex oscillators based on Co$_2$MnGe pseudo-spin valves

Dynamical influence of vortex–antivortex pairs in magnetic vortex oscillators

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