Effect of defects in Heusler alloy thin films on spin-dependent tunnelling characteristics of Co2MnSi/MgO/Co2MnSi and Co2MnGe/MgO/Co2MnGe magnetic tunnel junctions
Effect of defects in Heusler alloy thin films on spin-dependent tunnelling characteristics of Co2MnSi/MgO/Co2MnSi and Co2MnGe/MgO/Co2MnGe magnetic tunnel junctions
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DOI：
10.1088/0953-8984/22/16/164212
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发表时间：
2010-04
期刊：
影响因子：
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通讯作者：
Masafumi Yamamoto;T. Ishikawa;T. Taira;Gui-fang Li;K. Matsuda;T. Uemura
中科院分区：
文献类型：
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作者：
Masafumi Yamamoto;T. Ishikawa;T. Taira;Gui-fang Li;K. Matsuda;T. Uemura
在Co2MnαSi/MgO/Co2MnαSi MTJs中，采用不同Mn组成α值的Co2MnαSi，制备了co基Heusler合金Co2MnSi电极和MgO隧道势垒的全外延磁隧道结（MTJs）。在4.2 K和室温（RT）下，随着α的增加，缺锰成分（α 1）的Co2MnαSi电极的隧道磁电阻（TMR）率均有系统地增加，其中含富锰成分（α = 1.29）的Co2MnαSi电极在4.2 K和RT下的隧道磁电阻（TMR）率分别为1135%和236%。同样制备的co2mn - β geδ /MgO/ co2mn - β geδ (δ = 0.38) MTJs的TMR比率与Mn成分β有相似的依赖性，在4.2 K时TMR比率为650%，在β = 1.40时TMR比率为220%。Co2MnSi/MgO/Co2MnSi和Co2MnGe/MgO/Co2MnGe MTJs在4.2 K和RT下的TMR比对Mn组分的依赖可归因于富Mn Co2MnSi和Co2MnGe电极在费米能级附近抑制了少数自旋隙态。
Fully epitaxial magnetic tunnel junctions (MTJs) with Co-based Heusler alloy Co2MnSi electrodes and a MgO tunnel barrier were fabricated with various values of Mn composition α for Co2MnαSi in Co2MnαSi/MgO/Co2MnαSi MTJs. The tunnel magnetoresistance (TMR) ratios at both 4.2 K and room temperature (RT) increased systematically with increasing α in Co2MnαSi electrodes from Mn-deficient compositions (α 1), demonstrating high TMR ratios of 1135% at 4.2 K and 236% at RT for MTJs with Mn-rich Co2MnαSi electrodes with α = 1.29. Identically fabricated Co2MnβGeδ/MgO/Co2MnβGeδ (δ = 0.38) MTJs showed similar dependence of the TMR ratio on Mn composition β, demonstrating relatively high TMR ratios of 650% at 4.2 K and 220% at RT for β = 1.40. The Mn composition dependence of the TMR ratio at both 4.2 K and RT observed commonly for both Co2MnSi/MgO/Co2MnSi and Co2MnGe/MgO/Co2MnGe MTJs can be attributed to suppressed minority-spin in-gap states around the Fermi level for Mn-rich Co2MnSi and Co2MnGe electrodes.