超越亚微米尺度的二元性：交叉椭圆MTJ自由层作为自旋电子交叉阵列的多态单元
Beyond binary at submicron dimensions: crossed-ellipse MTJ free layers as multi-state cells for spintronic crossbars
- Bar-Ilan University（巴伊兰大学）
- Université catholique de Louvain（天主教鲁汶大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文通过微磁模拟研究交叉椭圆MTJ自由层的尺寸和长宽比对多态开关行为的影响，发现可调控出多达十二个剩磁态，为多态自旋电子交叉阵列提供几何设计窗口。
AI中文摘要：
自旋电子交叉阵列是用于节能神经形态计算的有前景的硬件平台，但传统的磁隧道结（MTJ）是二元的，限制了每个交叉点的信息密度和突触精度。本文使用MuMax3微磁模拟研究尺寸和长宽比如何控制交叉椭圆MTJ自由层的开关和剩磁态景观，以坡莫合金为主要模型系统，并用CoFeB检查可转移性。在固定的8:1长宽比下，将器件从16微米×2微米缩小到80纳米×10纳米会降低绝对开关电流，但将开关场从约11奥斯特提高到约301奥斯特，并增加了自旋轨道转矩（SOT）电流密度。在固定长轴为1.6微米时，长宽比调节产生低场四态区域，而较低的长宽比稳定了额外的具有较低开关场和电流密度的剩磁态。一个1.6微米×0.8微米的器件在其角度分辨平面霍尔响应中表现出十二个可访问的剩磁平台，可分辨的状态数取决于长宽比和绝对尺寸。投影的MTJ读出提供多个电平，而最小能量路径计算表明这十二种构型并非全部热独立。独立的MuMax+计算重现了多态拓扑，并揭示了标称上相距遥远的状态之间的低势垒多步逃逸路径。这些结果定义了可扩展多态自旋电子交叉阵列单元的几何依赖设计窗口。
英文摘要：
Spintronic crossbars are promising hardware platforms for energy-efficient neuromorphic computing, but conventional magnetic tunnel junctions (MTJs) are binary, limiting the information density and synaptic precision of each crosspoint. Here, MuMax3 micromagnetic simulations are used to investigate how size and aspect ratio control the switching and remanent-state landscape of crossed-ellipse MTJ free layers, with permalloy as the main model system and CoFeB checks for transferability. At fixed 8:1 aspect ratio, shrinking the device from 16 micron x 2 micron to 80 nm x 10 nm lowers the absolute switching current but raises the switching field from about 11 Oe to about 301 Oe and increases the SOT current density. At fixed major axis 1.6 micron, aspect-ratio tuning produces a low-field four-state regime, while lower aspect ratios stabilize additional remanent states with lower switching fields and current densities. A 1.6 micron x 0.8 micron device exhibits twelve accessible remanent plateaus in its angle-resolved planar Hall response, with the resolved state count depending on both aspect ratio and absolute size. Projected MTJ readout gives multiple electrical levels, while minimum-energy-path calculations show that the twelve configurations are not all thermally independent. Independent MuMax+ calculations reproduce the multistate topology and reveal lower-barrier multistep escape pathways between nominally distant states. These results define a geometry-dependent design window for scalable multistate spintronic crossbar cells.
