Multiscale Micromagnetic/Atomistic Modeling of Heat-Assisted Magnetic Recording

IF 1.9 3区 工程技术 Q3 ENGINEERING, ELECTRICAL & ELECTRONIC
Mohammed Gija;Alexey Dobrynin;Kevin McNeill;Mark Gubbins;Tim Mercer;Philip Bissell;Serban Lepadatu
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Abstract

Heat-assisted magnetic recording (HAMR) is a recent advancement in magnetic recording, allowing for a significant increase in the areal density capability (ADC) of hard disk drives (HDDs) compared to the perpendicular magnetic recording (PMR) technology. This is enabled by high anisotropy FePt media, which needs to be heated through its Curie temperature ( $T_{C}$ ) to facilitate magnetization reversal by an electromagnetic write pole. HAMR micromagnetic modeling is, therefore, challenging, as it needs to be performed in proximity to and above $T_{C}$ , where a ferromagnet has no spontaneous magnetization. An atomistic model is an optimal solution here, as it does not require any parameter renormalization or non-physical assumptions for modeling at any temperature. However, a full-track atomistic recording model is extremely computationally expensive. Here, we demonstrate a true multiscale HAMR modeling approach, combining atomistic spin dynamics (ASD) modeling for high-temperature regions and micromagnetic modeling for lower-temperature regions, in a moving simulation window embedded within a long magnetic track. The advantages of this approach include the natural emergence of $T_{C}$ and anisotropy distributions of FePt grains. Efficient GPU optimization of the code provides very fast running times, with a 60 nm wide track of 25 20 nm long bits being recorded in several hours on a single GPU. The effects of realistic FePt L10 versus simple cubic (SC) crystal structure are discussed, with the latter providing further running time gains while keeping the advantages of the multiscale approach.
热辅助磁记录的多尺度微磁/原子建模
热辅助磁记录(HAMR)是磁记录的最新进展,与垂直磁记录(PMR)技术相比,可以显着提高硬盘驱动器(hdd)的面密度能力(ADC)。这是通过高各向异性FePt介质实现的,该介质需要加热到居里温度($T_{C}$),以促进电磁写极的磁化反转。因此,HAMR微磁建模是具有挑战性的,因为它需要在$T_{C}$附近及以上进行,其中铁磁体没有自发磁化。原子模型是这里的最佳解决方案,因为它不需要任何参数重整化或在任何温度下进行建模的非物理假设。然而,全轨道原子记录模型在计算上是非常昂贵的。在这里,我们展示了一种真正的多尺度HAMR建模方法,结合了高温区域的原子自旋动力学(ASD)建模和低温区域的微磁建模,在嵌入在长磁轨道中的移动仿真窗口中。该方法的优点包括$T_{C}$的自然出现和FePt晶粒的各向异性分布。高效的GPU优化代码提供了非常快的运行时间,在单个GPU上记录一个60纳米宽的25个20纳米长的位在几个小时内。讨论了实际的FePt L10与简单立方(SC)晶体结构的影响,后者在保持多尺度方法优势的同时提供了进一步的运行时间增益。
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来源期刊
IEEE Transactions on Magnetics
IEEE Transactions on Magnetics 工程技术-工程:电子与电气
CiteScore
4.00
自引率
14.30%
发文量
565
审稿时长
4.1 months
期刊介绍: Science and technology related to the basic physics and engineering of magnetism, magnetic materials, applied magnetics, magnetic devices, and magnetic data storage. The IEEE Transactions on Magnetics publishes scholarly articles of archival value as well as tutorial expositions and critical reviews of classical subjects and topics of current interest.
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