Write Error Rate of Spin-Transfer-Torque Random Access Memory Including Micromagnetic Effects Using Rare Event Enhancement
Write Error Rate of Spin-Transfer-Torque Random Access Memory Including Micromagnetic Effects Using Rare Event Enhancement
复制标题
使用稀有事件增强的自旋转移矩随机存取存储器（包括微磁效应）的写入错误率
DOI：
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发表时间：
2016
影响因子：
2.1
通讯作者：
S. Banerjee
中科院分区：
文献类型：
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作者：
Urmimala Roy;T. Pramanik;L. Register;S. Banerjee
自旋转移矩随机存取存储器（STT-RAM）由于改进的可扩展性、读写速度和耐久性而成为下一代随机存取存储器的有希望的候选者。然而，写入脉冲持续时间必须足够长以确保低写入错误率（WER），即在存在随机热效应的情况下，在写入脉冲被关断之后位将保持未切换的概率。希望WER的标度为10-9或更低。在大自旋近似下，可以使用福克-普朗克方法分析计算WER。然而，钻头内的动态微磁效应会影响并导致更快的切换。这种微磁效应可以通过随机Landau-Lifshitz-Gilbert-Slonczewski（LLGS）方程的数值解来解决。然而，确定接近10-9的WER将需要远远超过109个这样的独立模拟，这是不可行的。在本文中，我们将探讨使用稀有事件增强（REE），已被用于其他系统的Monte Carlo模拟，稀有事件仍然很重要的方法，WER的计算。使用一个原型REE的方法量身定制的STT-RAM开关物理，我们证明了可靠的计算WER到10-9与组只有大约103个正在进行的随机LLGS模拟，和明显的能力，走得更远。
Spin-transfer-torque random access memory (STT-RAM) is a promising candidate for the next generation of random access memory due to improved scalability, read-write speeds, and endurance. However, the write pulse duration must be long enough to ensure a low write error rate (WER), the probability that a bit will remain unswitched after the write pulse is turned OFF, in the presence of stochastic thermal effects. WERs on the scale of 10-9 or lower are desired. Within a macrospin approximation, WERs can be calculated analytically using the Fokker-Planck method to this point and beyond. However, dynamic micromagnetic effects within the bit can affect and lead to faster switching. Such micromagnetic effects can be addressed via numerical solution of the stochastic Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation. However, determining WERs approaching 10-9 would require well over 109 such independent simulations, which is infeasible. In this paper, we explore the calculation of WER using rare event enhancement (REE), an approach that has been used for Monte Carlo simulation of other systems where rare events nevertheless remain important. Using a prototype REE approach tailored to the STT-RAM switching physics, we demonstrate reliable calculation of a WER to 10-9 with sets of only approximately 103 ongoing stochastic LLGS simulations, and the apparent ability to go further.