Low-Barrier Nanomagnets as p-Bits for Spin Logic
Low-Barrier Nanomagnets as p-Bits for Spin Logic
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DOI：
10.1109/lmag.2017.2685358
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发表时间：
2017-01-01
影响因子：
1.2
通讯作者：
Datta, Supriyo
中科院分区：
文献类型：
--
作者：
Faria, Rafatul;Camsari, Kerem Yunus;Datta, Supriyo
最近有研究表明，一个由可调谐电报噪声发生器或“p位”组成的适当互连网络，甚至可以用来执行像32位加法器这样的精确算术功能。在这封信中，我们使用基于随机Landau-Lifshitz-Gilbert （sLLG）方程的模拟来证明，使用能量势垒低至kT的一小部分的不稳定纳米磁体也可以实现类似的令人印象深刻的功能。这是令人惊讶的，因为低势垒纳米磁体的磁化强度不具有+/- 1的离散值。相反，它在-1和+1之间的所有值之间随机波动，并且使用阈值装置读取输出磁体，该装置将所有正值转换为1，将所有负值转换为零。我们提出了基于slgl的模拟，演示了32位加法器的操作，具有数百个纳米磁体的网络，显示出非常精确的相关性：输入磁体{a}和{B}以及输出磁体{S}都随机波动，但数量a + B-S在零附近急剧达到峰值！当我们固定{A}和{B}时，和磁体{S}迅速收敛到S = A + B的唯一状态，使系统起加法器的作用。但与标准加法器不同的是，这个运算是可逆的。如果我们固定{S}和{B}，则剩余的磁体{A}收敛于差值A = S - B。这些例子强调了纳米磁学领域的新方向，即从稳定的高势垒磁体转向随机的低势垒磁体，这种磁体不仅可以在更低的电流下工作，而且更有希望继续缩小规模。
It has recently been shown that a suitably interconnected network of tunable telegraphic noise generators or "p-bits" can be used to perform even precise arithmetic functions like a 32-bit adder. In this letter, we use simulations based on the stochastic Landau-Lifshitz-Gilbert (sLLG) equation to demonstrate that similar impressive functions can be performed using unstable nanomagnets with energy barriers as low as a fraction of a kT. This is surprising because the magnetization of low-barrier nanomagnets is not telegraphic with discrete values of +/- 1. Rather, it fluctuates randomly among all values between -1 and +1, and the output magnets are read with a thresholding device that translates all positive values to one and all negative values to zero. We present sLLG-based simulations demonstrating the operation of a 32-bit adder, with a network of several hundred nanomagnets, exhibiting a remarkably precise correlation: The input magnets {A} and {B} as well as the output magnets {S} all fluctuate randomly and yet the quantity A + B-S is sharply peaked around zero! If we fix {A} and {B}, the sum magnets {S} rapidly converge to a unique state with S = A + B so that the system acts as an adder. But unlike standard adders, the operation is invertible. If we fix {S} and {B}, the remaining magnets {A} converge to the difference A = S - B. These examples emphasize a new direction for the field of nanomagnetics away from stable high-barrier magnets toward stochastic low-barrier magnets that not only operate with lower currents, but are also more promising for continued downscaling.