Analysis of Effective Field Gradient in Microwave-Assisted Magnetic Recording

Narita, Naoyuki; Yamada, Keiichi; Taguchi, T.; Matsumoto, Takuya; Koi, K.; Takeo, Akihiko

doi:10.1109/tmag.2014.2327235

Cited by 14 publications

(4 citation statements)

References 4 publications

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“…3(a), the horizontal ac field is plotted together with the SPT head field, where the two peaks have opposite chirality in 3D oscillation [1,16], and the peak closer to the main pole can assist the write process in MAMR. The vertical ac field (plotted in Fig.…”

Section: Resultsmentioning

confidence: 99%

Signal-to-Noise Ratio Improvement of MAMR on CoX/Pt Media

Zhao

Wang

et al. 2015

IEEE Trans. Magn.

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The signal-to-noise ratio (SNR) gain of microwave assisted magnetic recording (MAMR) with spin transfer oscillator (STO) is analyzed by a micromagnetic model simulating the write process on CoX/Pt media, by including the Voronoi polycrystalline microstructure built upon a regular mesh of micromagnetic cells. With a fixed head of 40nm width main pole and 10.5 kOe maximum perpendicular field, a 2dB SNR gain is found for low coercivity media (0K Hc<10 kOe) and a 4dB gain is obtained for high coercivity media (0K Hc>14 kOe). Besides, the MAMR performance considering the finite rise time of single-pole-type (SPT) head field in a bit is also calculated. It is found that the MAMR SNR gain is obtained in the media with lower anisotropy because of the weak writing capacity during the rise time.Index Terms-microwave assisted magnetic recording (MAMR), spin transfer oscillator (STO), CoX/Pt media, signal to noise (SNR). 0018-9464 (c)

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Section: Resultsmentioning

confidence: 99%

Signal-to-Noise Ratio Improvement of MAMR on CoX/Pt Media

Zhao

Wang

et al. 2015

IEEE Trans. Magn.

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“…In particular, STT has been employed in various cutting-edge technologies including microwaveassisted magnetic recording in hard-disk drives and magnetoresistive random-access memories. [3][4][5][6][7][8] Recently, the emergence of spin-torque oscillations (STOs) has sparked considerable interest for their potential applications in neural networks. [9][10][11] While conventional ferromagnetic transition metals exhibit STO frequencies in the order of several gigahertz, [12][13][14][15] antiferromagnetic materials can theoretically manifest STO frequencies reaching the terahertz range.…”

Section: Introductionmentioning

confidence: 99%

Biquadratic magnetic coupling effect in CoPt/Cr/Fe₉₀Co₁₀ orthogonal structures

Liu,

Kurokawa,

Hashimoto

et al. 2024

Jpn. J. Appl. Phys.

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In this work, we present the biquadratic field Hbq contribution to increase a frequency of spin-torque oscillation (STO) in an orthogonal magnetization structure in simulation, and realize such an orthogonal structure by preparing Co/Pt lamination as the bottom perpendicular magnetic anisotropy (PMA) layer, Cr or Cu as the spacer, and experimentally realize Fe90Co10 as the top free layer. Our observations of the Cr-spacer sample reveal a notable challenge in achieving magnetic saturation, underscoring the role of Hbq in suppressing magnetization reversal and its potential to broaden the STO current range and increase the STO frequency. This leads to the manifestation of spin-transfer-torque oscillations in an orthogonal structure, bolstered by robust biquadratic magnetic coupling, thus attaining high and stable STOs in the simulations.

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“…With the same spirit of improving computational efficiency, a multiscale method has been proposed by Bruckner et al (2013), which only discretizes regions where detailed information such as domain walls and vortex structures are required. Other works have achieved the goal of accelerating the computational speed of micromagnetic problems by parallelizing the algorithms, such as a fast Fourier transform algorithm proposed by Tsukahara et al (2016), as well as finite-element algorithms proposed by Scholz et al (2003) and Narita et al (2014). Recently Fu et al (2015) have extended OOMMF with GPU implementation and has demonstrated 35× speedup compared to CPUs.…”

Section: Introductionmentioning

confidence: 99%

A massively parallel time-domain coupled electrodynamics–micromagnetics solver

Yao

Jambunathan

Zeng

et al. 2022

The International Journal of High Performance Computing Applica

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We present a high-performance coupled electrodynamics–micromagnetics solver for full physical modeling of signals in microelectronic circuitry. The overall strategy couples a finite-difference time-domain approach for Maxwell’s equations to a magnetization model described by the Landau–Lifshitz–Gilbert equation. The algorithm is implemented in the Exascale Computing Project software framework, AMReX, which provides effective scalability on manycore and GPU-based supercomputing architectures. Furthermore, the code leverages ongoing developments of the Exascale Application Code, WarpX, which is primarily being developed for plasma wakefield accelerator modeling. Our temporal coupling scheme provides second-order accuracy in space and time by combining the integration steps for the magnetic field and magnetization into an iterative sub-step that includes a trapezoidal temporal discretization for the magnetization. The performance of the algorithm is demonstrated by the excellent scaling results on NERSC multicore and GPU systems, with a significant (59×) speedup on the GPU using a node-by-node comparison. We demonstrate the utility of our code by performing simulations of an electromagnetic waveguide and a magnetically tunable filter.

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Analysis of Effective Field Gradient in Microwave-Assisted Magnetic Recording

Cited by 14 publications

References 4 publications

Signal-to-Noise Ratio Improvement of MAMR on CoX/Pt Media

Signal-to-Noise Ratio Improvement of MAMR on CoX/Pt Media

Biquadratic magnetic coupling effect in CoPt/Cr/Fe₉₀Co₁₀ orthogonal structures

A massively parallel time-domain coupled electrodynamics–micromagnetics solver

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Analysis of Effective Field Gradient in Microwave-Assisted Magnetic Recording

Cited by 14 publications

References 4 publications

Signal-to-Noise Ratio Improvement of MAMR on CoX/Pt Media

Signal-to-Noise Ratio Improvement of MAMR on CoX/Pt Media

Biquadratic magnetic coupling effect in CoPt/Cr/Fe90Co10 orthogonal structures

A massively parallel time-domain coupled electrodynamics–micromagnetics solver

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Product

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Biquadratic magnetic coupling effect in CoPt/Cr/Fe₉₀Co₁₀ orthogonal structures