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中国物理学会期刊

基于压控应变和SOT时钟协同调控的MRAM单元结构超低功耗翻转

Ultra-Low Energy Consumption Switching of MRAM Cell Structure Based on Synergistic Regulation of Voltage Controlled Strain and SOT Clocking

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  • 单一物理效应调控磁矩翻转,难以兼顾磁性随机存取存储器(MRAM)对“低能耗、高速度、高稳定性、全电学调控”的综合需求。为此,本文提出基于压控应变和自旋轨道矩(SOT)时钟协同调控的MRAM单元结构,其由磁性隧道结、重金属材料和压电衬底构成。通过建立多铁异质结磁化动力学模型,采用MuMax3微磁学仿真研究压控应变和SOT时钟作用下多铁纳磁体的磁矩翻转特性。结果表明:协同调控克服了单一时钟调控的缺陷,可在零磁场下实现多铁纳磁体磁矩的确定性翻转,提高了器件工作的可靠性;相比单一时钟调控的高能耗,协同调控能耗更低,单个周期耗能约6.4aJ/bit,较传统SOT调控能耗降低3个数量级,且写入速度更快。本研究为低功耗MRAM设计及磁性存储应用提供了重要的理论指导和技术支撑。

    Magnetoresistive Random Access Memory (MRAM) based on spintronic technology boasts non-volatility, high read/write speed and efficiency, compatibility with Complementary Metal-Oxide-Semiconductor (CMOS) manufacturing processes, excellent durability, and high integration density, emerging as one of the most promising storage technologies in the post-Moore era. Magnetization switching, the core operation of MRAM devices, directly determines device performance through its energy consumption, speed, and stability. Among the commonly used switching mechanisms for MRAM, the conventional magnetic field-driven magnetization switching relies on an external strong magnetic field, facing bottlenecks of high integration difficulty and high energy consumption; spin-transfer torque (STT)-driven switching requires a high critical current density, leading to severe Joule heating loss, and direct current penetration through the magnetic layer easily induces interface scattering and material damage, limiting device miniaturization, long lifespan, and stability; spin-orbit torque (SOT)-driven switching alone also requires a relatively high critical current density, which not only causes significant Joule heating loss but also aggravates enhanced spin scattering and electromigration damage at the heavy metal/ferromagnetic layer interface, reducing device writing endurance and long-term stability; voltage-controlled strain-driven switching alone can only induce a 90° magnetization rotation, requiring additional magnetic field or current assistance to achieve 180° deterministic magnetization reversal.
    To address these issues, this paper proposes an MRAM cell structure based on the synergistic regulation of voltage-controlled strain and SOT clocking, and conducts a detailed analysis of the optimized design of device materials and dimensional parameters. A magnetization dynamic model of the device was established using the MuMax3 micromagnetic simulation software, and the magnetization switching behaviors of the nanomagnet under individual regulation and synergistic regulation of the voltage-controlled strain clock and the SOT clock were investigated respectively. The simulation results show that, in contrast to the inability of voltage-controlled strain alone to achieve deterministic magnetization reversal of the nanomagnet, the proposed method can realize deterministic magnetization reversal without applying an auxiliary magnetic field, thereby improving the reliability of device operation. Based on the synergistic effect of the voltage-controlled strain clock and the SOT clock, no special device structures or materials are required, which does not increase the difficulty of the fabrication process. It exhibits significant advantages of ultra-low energy consumption and fast switching speed. The research findings indicate that compared with the high energy consumption of the SOT clock alone, the synergistic regulation achieves ultra-low energy consumption for nanomagnet switching, and the operating frequency can reach more than 6 times that of the SOT-only regulation. Calculations show that the energy consumption of the multiferroic nanomagnet device per cycle is approximately 6.4 aJ/bit, which is reduced by three orders of magnitude compared with the traditional SOT regulation method, while the writing speed is faster. The present study provides important theoretical guidance and technical support for the design of low-power MRAM and magnetic storage applications.

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