Sensitivity of the Power Spectra of Thermal Magnetization Fluctuations in Low Barrier Nanomagnets Proposed for Stochastic Computing to In-Plane Barrier Height Variations and Structural Defects
Sensitivity of the Power Spectra of Thermal Magnetization Fluctuations in Low Barrier Nanomagnets Proposed for Stochastic Computing to In-Plane Barrier Height Variations and Structural Defects
复制标题
提出用于随机计算的低势垒纳米磁体中热磁化涨落功率谱对面内势垒高度变化和结构缺陷的敏感性
DOI：
10.1142/s2010324720500010
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发表时间：
2020
期刊：
影响因子：
1.8
通讯作者：
Supriyo Bandyopadhyay
中科院分区：
文献类型：
--
作者：
Md Ahsanul Abeed;Supriyo Bandyopadhyay
平面内部各向异性能量屏障的纳米磁体在热能阶的范围内具有不稳定的磁化化，这些磁性会随着时间的及时而随机波动。位。在纳米磁体的屏障高度（由小尺寸变化引起）和（ii）存在结构缺陷（既有局部和离域），以评估基于低屏障纳米磁体（LBM）的稳健计算平台发现功率谱密度对现代屏障高度的变化相对不敏感，并且对局部缺陷的存在相对不敏感。纳米磁体的大量厚度的变化非常明显，这意味着扩展的缺陷会显着改变磁化磁化强度的波动率。对后者的严重影响。高度及其制造的基材可能具有与纳米磁体厚度相当的表面粗糙度。 ）屏障高度的微小变化或局部小缺陷是相对无害的，但不得不避免后者。随机计算应用。
Nanomagnets with small in-plane shape anisotropy energy barriers on the order of the thermal energy have unstable magnetization that fluctuates randomly in time. They have recently emerged as promising hardware platforms for stochastic computing and machine learning because the random magnetization states can be harnessed for probabilistic bits. Here, we have studied how the statistics of the magnetization fluctuations (e.g., the power spectral density) is affected by (i) moderate variations in the barrier height of the nanomagnet (caused by small size variations) and (ii) the presence of structural defects — both localized and delocalized — in order to assess how robust the stochastic computing platform based on Low Barrier Nanomagnets (LBM) is. We found that the power spectral density is relatively insensitive to moderate barrier height change and also relatively insensitive to the presence of small localized defects. However, extended (delocalized) defects, such as thickness variations over a significant fraction of the nanomagnet, affect the power spectral density very noticeably. That means extended defects can significantly alter the fluctuation rate of the magnetization in low barrier nanomagnets. Since the fluctuation rate is crucial for stochastic computing applications, this has very serious implications for the latter. Thickness variations are difficult to avoid in real nanomagnets with in-plane anisotropy since they must be thin to keep the barrier height small and the substrate on which they are fabricated may have surface roughness comparable to the nanomagnet thickness. This raises questions about the viability of stochastic computing with low barrier nanomagnets possessing in-plane anisotropy. Our results establish that small variations in the shape (causing small variations in the barrier height), or small localized defects, are relatively innocuous and tolerable but extended defects are not. The latter must be avoided for stochastic computing applications.
影响因子：
1.2
作者：
Debashis, Punyashloka;Faria, Rafatul;Chen, Zhihong
通讯作者：
Chen, Zhihong
影响因子：
1.2
作者：
Hassan, Orchi;Faria, Rafatul;Datta, Supriyo
通讯作者：
Datta, Supriyo