CN101593601A - 一种半金属合成反铁磁结构 - Google Patents

一种半金属合成反铁磁结构 Download PDF

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CN101593601A
CN101593601A CNA200910081790XA CN200910081790A CN101593601A CN 101593601 A CN101593601 A CN 101593601A CN A200910081790X A CNA200910081790X A CN A200910081790XA CN 200910081790 A CN200910081790 A CN 200910081790A CN 101593601 A CN101593601 A CN 101593601A
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magnetic
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semimetal
synthetic anti
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徐晓光
张德林
姜勇
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University of Science and Technology Beijing USTB
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Abstract

一种半金属合成反铁磁结构,属于磁存储技术领域。其特征在于:以所有Co占据A位置的A2BC型Heusler合金材料作为磁性层,制备出半金属层/钌层/半金属层的三明治结构,两个半金属层的磁化方向实现了反铁磁耦合。本发明的优点在于:在半金属合成反铁磁结构中,半金属材料中的钴元素可以与金属钌形成强反铁磁耦合,保证了三层膜的反铁磁耦合构型,同时,采用高自旋极化率,低饱和磁化强度和低矫顽力的半金属材料作为磁性层,能够使器件的磁翻转场降低,磁电阻率和热稳定性提高,进而使超高存储密度成为可能。

Description

一种半金属合成反铁磁结构
技术领域
本发明属于磁存储技术领域,提供了一种半金属合成反铁磁结构,具有高磁灵敏性及高热稳定性。这种以半金属材料为磁性层的合成反铁磁结构能够降低控制能耗,应用于自旋阀和磁隧道结中能够提高磁电阻,进而实现超高存储密度,将被广泛应用于新型磁传感器或磁随机存储器等器件中。
背景技术
自旋阀(Spin Valve,简称SPV)结构(铁磁层/铜/铁磁层/反铁磁层)和磁隧道结(Magnetic Tunneling Junction,简称MTJ)结构(铁磁层/氧化物/铁磁层/反铁磁层)自问世以来,已经被广泛应用于磁读出头、磁随机存储器和磁敏传感器等领域。提高磁存储密度的关键在于减小磁存储单元和磁头的尺寸,然而,随着器件尺寸的减小,自由层的纵横比减小,退磁场急剧增加,甚至导致SPV中的铁磁薄膜出现复杂的多磁畴状态,改变自由层磁化方向所需的磁翻转场强度急剧升高,控制能耗增高,热稳定性降低。“合成反铁磁”(Synthetic Antiferromagnet,简称SyAF)结构的出现解决了这一难题。SyAF是由两个铁磁性层和中间一个极薄的金属钌层所组成的三层膜复合结构,通常当钌层的厚度小于1nm时,两铁磁性层在较宽温度范围内呈强反铁磁性耦合,在膜结构中磁通线为闭合状态,避免了退磁场的影响[K.Inomata,T.Nozaki,N.Tezuka,and S.Sugimoto,Appl.Phys.Lett.81,310(2002),Z.Q.Lu and G.H.Pan,J.Appl.Phys.91,7116(2002)]。由于SyAF耦合状态的特殊性,它可以用来取代SPV和MTJ中的自由层[Y.Jiang,S.Abe,T.Nozaki,N.Tezuka,and K.Inomata,IEEE Trans.Magn.40,issue4,part2,2245(2004)]或者被钉扎层[Y.Huai,J.Zhang,G.W.Anderson,P.Rana,S.Funada,C.-Y.Hung,M.Zhao and S.Tran,J.Appl.Phys.85,5528(1999)],从而提高SPV和MTJ的磁翻转性能和对外加磁场的反应灵敏度。目前使用的SPV和MTJ中都包含合成反铁磁结构。
半金属材料是一种具有高自旋极化率的磁性材料,其理论自旋极化率为100%,其中钴基半金属Heusler合金材料的磁学性质适用于SPV和MTJ,并成功获得高磁电阻效应的器件。钴基半金属Heusler合金材料相对于目前合成反铁磁结构中的铁磁层材料(钴铁合金或镍铁合金),具有更低的矫顽力和饱和磁化强度,更高的自旋极化率。
发明内容
本发明目的在于提供一种具有高磁灵敏性和高热稳定性的半金属合成反铁磁结构,以获得高磁电阻效应的器件,提高SyAF的磁灵敏性和热稳定性,最终实现超高磁存储密度。
一种半金属合成反铁磁结构,合成反铁磁结构通过常规的薄膜沉积设备(例如等离子体溅射、磁控溅射或者分子束外延生长等等)制备而成。结构中上下二层均为半金属层,半金属层材料种类包括所有Co占据A位置的A2BC型Heusler合金材料,厚度为2~30纳米;中间一层为金属钌层,厚度为0.4~1纳米。利用半金属中的钴元素,在半金属层/钌层/半金属层的三明治结构中形成强反铁磁耦合;同时利用钴基半金属材料的高自旋极化率,低饱和磁化强度和低矫顽力,提高合成反铁磁结构的磁灵敏性和热稳定性,从而实现低磁翻转能耗和高使用温度。
如上所述Co占据A位置的A2BC型Heusler合金材料包括Co2FeAl、Co2FeSi、Co2MnSi、Co2CrAl、Co2Fe(Al1-xSix)(0<x<1)、Co2(Fe1-xMnx)Si(0<x<1)等。
本发明的优点在于:在半金属合成反铁磁结构中,半金属材料中的钴元素可以与金属钌形成强反铁磁耦合,保证了三层膜的反铁磁耦合构型,同时,采用高自旋极化率,低饱和磁化强度和低矫顽力的半金属材料作为磁性层,能够使器件的磁翻转场降低,磁电阻率和热稳定性提高,进而使更高存储密度成为可能。
具体实施方式
发明人根据上述结构,分别利用磁控溅射仪或分子束外延的方法制备了以下63种三层膜结构:其特点是以半金属材料[Co2FeAl、Co2FeSi、Co2MnSi、Co2CrAl、Co2Fe(Al1-xSix)(0<x<1)、Co2(Fe1-xMnx)Si(0<x<1)等Co占据A位置的A2BC型Heusler合金]为合成反铁磁结构的磁性层。上述三层膜的详细制备工艺为:溅射室本底真空度为2×10-5Pa,溅射时氩气(99.99%)压为0.5 Pa,基片用循环水冷却。
Figure A20091008179000051
Figure A20091008179000061
Figure A20091008179000071
通过测试,上述器件在不同程度上均可以实现强反铁磁耦合,磁翻转场低于10Oe。反铁磁耦合可以保持到400℃以上。这使得该结构完全可以运用在磁随机存储器和磁读出头等器件中,并实现超高密度信息存储。

Claims (2)

1、一种半金属合成反铁磁结构,其特征在于:以半金属材料作为磁性层,制备出半金属层/钌层/半金属层的三明治结构,两个半金属层的磁化方向呈反铁磁耦合;
具体结构为:
上下二层均为半金属层,半金属层材料种类包括所有Co占据A位置的A2BC型Heusler合金材料,厚度为2~30纳米;
中间一层为金属钌层,厚度为0.4~1纳米。
2、如权利要求1所述的半金属合成反铁磁结构,其特征在于其中半金属材料为Co2FeAl、Co2FeSi、Co2MnSi、Co2CrAl、Co2Fe(Al1-xSix)(0<x<1)或Co2(Fe1-xMnx)Si(0<x<1)。
CNA200910081790XA 2009-04-10 2009-04-10 一种半金属合成反铁磁结构 Pending CN101593601A (zh)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101752051A (zh) * 2010-03-05 2010-06-23 北京科技大学 一种垂直磁各向异性多层膜
CN103022345A (zh) * 2012-12-27 2013-04-03 河北工业大学 一种隧穿磁电阻多层膜材料
CN105405968A (zh) * 2015-11-03 2016-03-16 华中科技大学 一种调整半金属磁体电子能带结构的方法及其产物

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101752051A (zh) * 2010-03-05 2010-06-23 北京科技大学 一种垂直磁各向异性多层膜
CN101752051B (zh) * 2010-03-05 2011-07-20 北京科技大学 一种垂直磁各向异性多层膜
CN103022345A (zh) * 2012-12-27 2013-04-03 河北工业大学 一种隧穿磁电阻多层膜材料
CN105405968A (zh) * 2015-11-03 2016-03-16 华中科技大学 一种调整半金属磁体电子能带结构的方法及其产物

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