面向高密度磁随机存储器的B2-CoGa(Pt)/L1_(0)-MnAl双层膜中高自旋轨道矩效率  

Enhancement of spin-orbit torque efficiency in B2-CoGa(Pt)/L1_(0)-MnAl bilayers for high-density MRAM

作　　者：孙宏利 韩荣坤 魏大海 赵建华[1,2] Hongli Sun;Rongkun Han;Dahai Wei;Jianhua Zhao(State Key Laboratory of Semiconductor Physics and Chip Technologies,Institute of Semiconductors,Chinese Academy of Sciences,Beijing 100083,China;National Key Laboratory of Spintronics,Hangzhou International Innovation Institute,Beihang University,Hangzhou 311115,China)

机构地区：[1]中国科学院半导体研究所,半导体芯片物理与技术全国重点实验室,北京100083 [2]杭州市北京航空航天大学国际创新研究院(北京航空航天大学国际创新学院),自旋芯片与技术全国重点实验室,杭州311115

出　　处：《科学通报》2025年第7期920-928,共9页Chinese Science Bulletin

基　　金：中国科学院战略性先导科技专项(XDB44010100);中国科学院稳定支持基础研究领域青年团队计划(YSBR-030)资助;杭州市北京航空航天大学国际创新研究院科研启动经费(2024KQ01)。

摘　　要：Mn基二元合金L1_(0)-MnAl具有垂直磁各向异性强、自旋极化率高和磁阻尼因子低等特点,是研制高密度、高性能和低功耗磁随机存储器(magnetic random access memory,MRAM)的重要材料体系,而B2-CoGa合金则同时为外延生长在主流半导体GaAs上垂直磁各向异性L1_(0)-MnAl薄膜提供了理想的缓冲层和自旋流来源.本文报道了在B2-CoGa缓冲层中掺杂重金属Pt可以显著提高L1_(0)-MnAl/(CoGa)_(1-x)Pt_(x)双层膜中的自旋轨道矩(spin-orbit torque,SOT)效率.该双层膜在高达x=0.1的掺杂范围内仍然保持着良好的垂直磁各向异性,其磁矩实现翻转的临界电流密度可从4.63×10^(7)A/cm^(2)降低到2.59×10^(7)A/cm^(2),同时SOT效率从0.042提高到0.080.这种增强归因于在保持(CoGa)_(1-x)Pt_(x)有效自旋霍尔电导率不变的情况下其电阻率的增加.其中,x=0.075样品能够支持横向尺寸8.09 nm的磁性隧道结单元,同时功耗可降低至原来的0.63.这些结果为基于Mn基二元合金的MRAM研发提供了参考.Magnetic random-access memory(MRAM)has emerged as a leading candidate for next-generation storage technology,offering high speed,high density,non-volatility,low power consumption,and radiation resistance.MRAM has evolved through three generations:field-driven toggle MRAM,spin-transfer torque(STT)-MRAM,and the experimental spin-orbit torque(SOT)-MRAM.The current commercial MRAM products primarily rely on STT-MRAM,which is based on Ta/CoFeB/MgO multilayers with the interfacial perpendicular magnetic anisotropy(PMA).However,STT-MRAM performance deteriorates at sub-10 nm size due to thermal instability.In contrast,the tetragonal Mn-based binary alloys exhibit stable bulk PMA and enhanced properties for sub-10 nm tunnel junction devices.Previous research has demonstrated the potential of these alloys for high-density MRAM,with magnetization switching achieved via SOT without the need for external magnetic fields.Among Mn-based binary alloys,L1_(0)-MnAl stands out due to its strong PMA,high spin polarization,and low magnetic damping,making it a promising material for next-generation MRAM.On the other side,the B2-CoGa alloy serves as both an ideal buffer layer and a spin current source for the epitaxial growth of PMA L1_(0)-MnAl thin films on GaAs substrates.Our study demonstrates that doping B2-CoGa with Pt significantly enhances the SOT efficiency in(CoGa)_(1-x)Pt_(x)/L1_(0)-MnAl bilayers while preserving the excellent PMA properties of L1_(0)-MnAl.Experimental results show that Pt doping up to x=0.1 keeps the PMA characteristics while simultaneously reducing the critical current density required for magnetization switching from 4.63×10^(7)A/cm^(2)to 2.59×10^(7)A/cm^(2).SOT efficiency increases from 0.042 to 0.080.This enhancement is attributed to the increased resistivity of the(CoGa)_(1-x)Pt_(x)layer,which does not compromise its effective spin Hall conductivity.The optimized bilayer,with x=0.075,supports magnetic tunnel junctions with lateral size as small as 8.09 nm,reducing power consumption by 37%.The SOT effe

关 键 词：垂直磁各向异性 自旋轨道矩 Mn基二元合金 磁矩翻转 分子束外延 

分 类 号：TP3[自动化与计算机技术—计算机科学与技术]