【摘要】 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(15nm)/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La1-xSrxMnO3成分调制的复合磁性隧道结.在4·2K和外加磁场8T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.更多还原

【Abstract】 Tunnel magnetoresistance junctions with the structure of SrTiO₃-sub/La 0.7 Sr 0.3 MnO₃（100nm）/La 0.96 Sr 0.04 MnO₃ （5nm）/ La 0.7 Sr 0.3 MnO₃ （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 MnO₃（100nm）/La 0.96 Sr 0.04 MnO₃ （5nm）/La 0.7 Sr 0.3 MnO₃ （100nm） were deposited on single crystal （001） SrTiO₃-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 MnO₃ 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 MnO₃. The high TMR value can possibly be attributed to the good interface due to the perfect barrier.更多还原