论文标题
基于山谷旋转霍尔效应的非易失性记忆，具有启用读写路径的交换耦合电气隔离
Valley-Spin Hall Effect-based Nonvolatile Memory with Exchange-Coupling-Enabled Electrical Isolation of Read and Write Paths
论文作者
论文摘要
单层WSE2中的Valley-Spin Hall（VSH）效应已显示出对非易失性记忆（NVM）设计具有非常有益的特征。基于旋转轨道扭矩（SOT）-MRAM的基于VSH的磁随机记忆（VSH-MRAM）的关键优势包括访问无晶体管 - 无晶体紧凑型位细胞和垂直磁性各向异性（PMA）磁体的低功率转换。然而，由于WSE2和Schottky触点的迁移率较低，读取路径（RS）中的较大设备阻力会恶化感官边缘，从而抵消了VSH-MRAM的好处。为了解决这一限制，我们提出了另一种基于VSH的MRAM的味道（在遗传了VSH-MRAM的大多数好处时）通过电气隔离读写终端来实现读取路径中较低的RS。通过将VSH与电隔离但磁耦合的PMA磁体耦合，可以通过层间交换耦合来启用这一点。使用面向对象的微电磁框架（OOMMF）模拟设计提出的设备，我们确保在过程变化下交换耦合的PMA系统的鲁棒性。为了保持紧凑的内存足迹，我们在多个位细胞上共享读取访问晶体管。与现有的VSH-MRAM相比，我们的设计分别达到了39％-42％和36％-46％的读取时间和能量，以及在可比区域的1.1x-1.3倍。这分别以1.7倍和2.0倍的成本增加了写入时间和能量。因此，所提出的设计适用于读取比写作更主导的应用。
Valley-spin hall (VSH) effect in monolayer WSe2 has been shown to exhibit highly beneficial features for nonvolatile memory (NVM) design. Key advantages of VSH-based magnetic random-access memory (VSH-MRAM) over spin orbit torque (SOT)-MRAM include access transistor-less compact bit-cell and low power switching of perpendicular magnetic anisotropy (PMA) magnets. Nevertheless, large device resistance in the read path (RS) due to low mobility of WSe2 and Schottky contacts deteriorates sense margin, offsetting the benefits of VSH-MRAM. To address this limitation, we propose another flavor of VSH-based MRAM that (while inheriting most of the benefits of VSH-MRAM) achieves lower RS in the read path by electrically isolating the read and write terminals. This is enabled by coupling VSH with electrically-isolated but magnetically-coupled PMA magnets via interlayer exchange-coupling. Designing the proposed devices using object oriented micro magnetic framework (OOMMF) simulation, we ensure the robustness of the exchange-coupled PMA system under process variations. To maintain a compact memory footprint, we share the read access transistor across multiple bit-cells. Compared to the existing VSH-MRAMs, our design achieves 39%-42% and 36%-46% reduction in read time and energy, respectively, along with 1.1X-1.3X larger sense margin at a comparable area. This comes at the cost of 1.7X and 2.0X increase in write time and energy, respectively. Thus, the proposed design is suitable for applications in which reads are more dominant than writes.
