Chirped-microwave assisted magnetization reversal

Wang, Zihui; Wu, Mingzhong

doi:10.1063/1.3121075

Cited by 25 publications

(17 citation statements)

References 18 publications

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“…This phenomenon has been observed in atomic systems [18,19], plasmas [20,21], fluids [22], and semiconductor quantum wells [23]. Some earlier numerical and analytical studies [24][25][26] pointed out the efficiency of a chirped microwave field to induce the reversal of the magnetic moment in a nanoparticle, but did not exploit the analytical tools provided by the autoresonance theory.…”

Section: Introductionmentioning

confidence: 94%

Autoresonant switching of the magnetization in single-domain nanoparticles: Two-level theory

et al. 2015

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The magnetic moment of a single-domain nanoparticle can be effectively switched on an ultrashort time scale by means of oscillating (microwave) magnetic fields. This switching technique can be further improved by using fields with time-dependent frequency (autoresonance). Here, we provide a full theoretical framework for the autoresonant switching technique, by exploiting the analogy between the magnetization state of an isolated nanoparticle and a two-level quantum system, whereby the switching process can be interpreted as a population transfer. We derive analytical expressions for the threshold amplitude of the microwave field, with and without damping, and consider the effect of thermal fluctuations. Comparisons with numerical simulations show excellent agreement.

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Section: Introductionmentioning

confidence: 94%

Autoresonant switching of the magnetization in single-domain nanoparticles: Two-level theory

et al. 2015

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“…Theoretical simulations based on the Landaun-Lifshitz-Gilbert (LLG) equation have proved its potential to reduce H sw of the recording media. [6][7][8][9][10][11][12][13][14][15] The physical mechanism of MAS can be understood by the analytical model based on the single macrospin in the rotating frame. 15 Under the assistance of h rf , H sw linearly decreases with increasing the rf frequency f rf up to the critical frequency f c above which it suddenly increases and becomes the same as that in the absence of h rf .…”

mentioning

confidence: 99%

Size dependence of magnetization switching and its dispersion of Co/Pt nanodots under the assistance of radio frequency fields

Furuta¹,

Okamoto²,

Kikuchi³

et al. 2014

Journal of Applied Physics

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We have studied the dot size dependence of microwave assisted magnetization switching (MAS) on perpendicular magnetic Co/Pt multilayer dot array. The significant microwave assistance effect has been observed over the entire dot size D ranging from 50 nm to 330 nm examined in the present study. The MAS behavior, however, critically depends on D. The excitation frequency dependence of the switching field is well consistent with the spin wave theory, indicating that the magnetization precession in MAS is in accordance with the well defined eigenmodes depending on the dot diameter. The lowest order spin wave is only excited for D 100 nm, and then the MAS effect is well consistent with that of the single macrospin prediction. On the other hand, higher order spin waves are excited for D > 100 nm, giving rise to the significant enhancement of the MAS effect. The dispersion of MAS effect also depends on D and is significantly reduced for the region of D > 100 nm. This significant reduction of the dispersion is attributed to the essential feature of the MAS effect which is insensitive to the local fluctuation of anisotropy field, such as defect, damaged layer, and so on. V C 2014 AIP Publishing LLC. [http://dx.

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“…Some authors also noticed the beneficial effect of a chirped pulse on the magnetization dynamics in a nanoparticle [24][25][26], but lacked the analytical tools provided by the autoresonance theory. The autoresonance theory was used in the past to study the excitation of high-amplitude magnetization precession in ferromagnetic thin films [27] and the dynamics of localized magnetic inhomogeneities in a ferromagnet [28].…”

Section: Introductionmentioning

confidence: 99%

Autoresonant control of the magnetization switching in single-domain nanoparticles

Klughertz¹,

Hervieux

Manfredi

2014

J. Phys. D: Appl. Phys.

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The ability to control the magnetization switching in nanoscale devices is a crucial step for the development of fast and reliable techniques to store and process information. Here we show that the switching dynamics can be controlled efficiently using a microwave field with slowly varying frequency (autoresonance). This technique allowed us to reduce the applied field by more than 30% compared to competing approaches, with no need to fine-tune the field parameters. For a linear chain of nanoparticles the effect is even more dramatic, as the dipolar interactions tend to cancel out the effect of the temperature. Simultaneous switching of all the magnetic moments can thus be efficiently triggered on a nanosecond timescale. * Electronic address: manfredi@unistra.fr

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Chirped-microwave assisted magnetization reversal

Cited by 25 publications

References 18 publications

Autoresonant switching of the magnetization in single-domain nanoparticles: Two-level theory

Autoresonant switching of the magnetization in single-domain nanoparticles: Two-level theory

Size dependence of magnetization switching and its dispersion of Co/Pt nanodots under the assistance of radio frequency fields

Autoresonant control of the magnetization switching in single-domain nanoparticles

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