成分调制的La1－xSrxMnO3复合隧道结

利用磁控溅射和Sr成分的调制以及原位热处理方法，在10mm×10mm大小的(001) 取向SrTiO_３单晶衬底上制备出三明治结构为La_0.7Sr_0.3MnO３(100nm)/La_0.96Sr_0.04MnO_３ (5nm)/ La0.7Sr_0.3MnO_３ (100nm) 的隧道结外延薄膜，然后再次 利用磁控溅射方法，在三层单晶膜上方继续沉积Ir_２２Mn_７８(15n m)/Ni_７９Fe_２１(5nm)/Pt(20nm)等金属三层膜.最后利用深紫外曝 光和Ar离子束刻蚀等微加工技术，制备出长短轴分别为12和6μm或者8和4μm大小的椭圆形L a_１-xSr_xMnO_３成分调制的复合磁性隧道结.在4.2K和 外加磁场8 T的测试下，La_１-xSr_xMnO_３成分调制的复 合磁性隧道结其隧穿磁电阻(TMR)比值达到3270%, 直接从实验上证实了铁磁性La_{0.7Sr0.3MnO３金属氧化物的自旋极化率（97%）可接近100％，具 有很好的半金属性质. 关键词： １-x}Sr_xMnO_３')" href="#">La_１-xSr_xMnO_３ 半金属 成分调制 复合磁性隧道 结 隧穿磁电阻

Composition-modulated hybrid tunnel junctions of La1-x SrxMnO3

Tunnel magnetoresistance junctions with the structure of SrTiO_3-sub/La_ 0.7 Sr_ 0.3 MnO_3(100nm)/La_ 0.96 Sr_ 0.04 MnO_3 (5nm)/ La_ 0.7 Sr_ 0.3 MnO_3 (100nm)/Ir_ 22 Mn_ 78 (15nm)/Ni_ 79 Fe_ 21 (5nm)/Pt(20nm) were micro-fabricated with lithography and Ar ion etching. The first three epitaxial layers of La_ 0.7 Sr_ 0.3 MnO_3(100nm)/La_ 0.96 Sr_ 0.04 MnO_3 (5nm)/La_ 0.7 Sr_ 0.3 MnO_3 (100nm) were deposited on single crystal (001) SrTiO_3-substrate by magnetron sputtering and heat treatment, then the spinning and top conducting layers of Ir_ 22 Mn_ 78 (15nm)/Ni_ 79 Fe_ 21 (5nm)/Pt(20nm) were continuously fabricated on top the three epitaxial layers by normal magnetron sputtering. The colossal TMR ratio of 3270% was observed at 4.2K under the external magnetic field of 8 T. The polarization value of 97% for the La_ 0.7 Sr_ 0.3 MnO_3 is well consistent with the theoretical value of 100%. The present results directly indicate the half-metallic ferromagnetism in La_ 0.7 Sr_ 0.3 MnO_3. The high TMR value can possibly be attributed to the good interface due to the perfect barrier.