基于磁性隧道结和双组分多铁纳磁体的超低功耗磁弹模数转换器  

Ultra-low power magneto-elastic analog-to-digital converter based on magnetic tunnel junctions and bicomponent multiferroic nanomagnet

作　　者：夏永顺 杨晓阔[1] 豆树清 崔焕卿 危波 梁卜嘉 闫旭 Xia Yong-Shun;Yang Xiao-Kuo;Dou Shu-Qing;Cui Huan-Qing;Wei Bo Liang;Bu-Jia;Yan Xu(Basic Department,Air Force Engineering University,Xi’an 710051,China)

机构地区：[1]空军工程大学基础部,西安710051

出　　处：《物理学报》2024年第13期301-308,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:62274183,62301595);陕西省自然科学基础研究计划(批准号:2022JQ-073)资助的课题。

摘　　要：本文提出了一种由8个磁性隧道结(magnetic tunnel junction,MTJ)构成的3位磁弹模数转换器(magnetoelastic analog-to-digital converter,MEADC),该转换器中MTJ自由层为双组分多铁纳磁体.通过对多铁纳磁体实施应变介导的电压调控,可以实现零场条件下的确定性磁化翻转.研究发现:对于给定尺寸,给定材料的双组分多铁纳磁体,压电层厚度与双组分多铁纳磁体的临界翻转电压线性相关.基于该原理,通过调整压电层的厚度使得MEADC具有8个不同的电压切换阈值,将模拟信号转换为8个多铁MTJ不同磁化状态组合.同时,设计了锁存比较器和独立的读取电路来检测MTJ的阻态,以此实现了数字信号的输出.Monte Carlo功能模拟表明:该MEADC在室温下写入成功率可达100%;此外,读写电路相互分离,使得压电层厚度与MTJ的输出参考电压无关,因此每个MTJ可设置相同的参考电压,从而具有更高的读取可靠性.微磁仿真和数值模拟分析发现:该MEADC的工作频率可达250 MHz,单次转换能耗仅为20 aJ;与基于Racetr ack技术的磁模数转换器相比,能耗降低了1000倍,采样速率提高了10倍.本文提出的MEADC可为基于自旋电子器件的存算一体电路架构提供重要的技术支撑.In recent years,the utilization of artificial intelligence and big data has led to the rise of compute-inmemory signal processing as the primary method for ADC design.Spintronic memory devices,which have nonvolatile and low static power consumption characteristics,are particularly suitable for the design of low-power,high-bandwidth compute-in-memory ADCs.In this paper,a 3-bit magneto-elastic analog-to-digital converter(MEADC)is proposed,which comprises eight magnetic tunnel junctions(MTJs),where the MTJ free layer is a bicomponent multiferroic nanomagnet.The bicomponent multiferroic nanomagnet can attain deterministic magnetization switching under zero-field condition by regulating the strain-mediated voltage.It has been discovered that there is a linear correlation between the thickness of the piezoelectric layer and the critical flip voltage in a bicomponent multiferroic nanomagnet of a given size and material.Using this principle,the thickness of the piezoelectric layer is adjusted to allow the MEADC to have eight different voltage switching thresholds.This can make the analog signal converted into a combination of different magnetization states of eight multiferroic MTJ.A latch comparator and an independent read circuit are designed to detect the MTJ's resistance state output a digital signal.Monte Carlo simulations indicate that the MEADC can achieve a 100%success rate of writing at room temperature.Additionally,the read circuit and write circuit are separated from each other,thus the same reference voltage can be set for each MTJ and result in higher readability.Micromagnetic simulation and numerical analysis demonstrate that the MEADC can operate at a maximum frequency of 250 MHz,and the energy consumption of a single conversion is only 20 aJ.Compared with the magnetic analog-to-digital converter based on the Racetrack technology,the energy consumption is reduced by 1000 times,and the sampling rate is increased by10 times.The MEADC proposed in this paper offers an essential technical support for the spintr

关 键 词：磁弹模数转换器 磁性隧道结 自旋电子学 纳磁体 

分 类 号：O469[理学—凝聚态物理]