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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SrTiO３单晶衬底上制备出三明治结构为La0.7Sr0.3MnO３(100nm)/La0.96Sr0.04MnO３ (5nm)/ La0.7Sr0.3MnO３ (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Ir２２Mn７８(15n m)/Ni７９Fe２１(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 a１-xSrxMnO３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，La１-xSrxMnO３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La0.7Sr0.3MnO３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.
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关键词:
- La１-xSrxMnO３ /
- 半金属 /
- 成分调制 /
- 复合磁性隧道 结 /
- 隧穿磁电阻
Tunnel magnetoresistance junctions with the structure of SrTiO３-sub/ La0.7Sr0.3MnO３(100nm)/La0.96Sr 0.04MnO３ (5nm)/La0.7Sr0.3MnO３ (100nm)/Ir２２Mn７８(15nm)/Ni７９Fe２１(5nm)/Pt(20nm) were micro-fabricated with lithography and Ar ion etching. T he first three epitaxial layers of La0.7Sr0.3MnO３(100nm)/La0.96Sr0.04MnO３ (5nm)/La0.7Sr0.3MnO３ (100nm) were deposited on single crystal (0 01) SrTiO３-substrate by magnetron sputtering and heat treatment, the n the spinning and top conducting layers of Ir２２Mn７８(1 5nm)/Ni７９Fe２１(5nm)/Pt(20nm) were continuously fabricat ed on top the three epitaxial layers by normal magnetron sputtering. The coloss al TMR ratio of 3270% was observed at 4.2K under the external magnetic field of 8 T. The polarization value of 97% for the La0.7Sr0.3MnO３ is well consistent with the theoretical value of 100%. The present r esults directly indicate the half-metallic ferromagnetism in La0.7Sr0.3MnO３. The high TMR value can possibly be attributed to the good interface due to the perfect barrier.-
Keywords:
- La１-xSrxMnO３ /
- half-metallic ferrom agnet /
- compositionally modulated /
- hybrid tunnel junctions /
- tunneling magnetore sistance
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中国物理学会期刊
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