Magnetoresistance and microstructure of magnetite nanocrystals dispersed in indium-tin oxide thin films.
Magnetoresistance and microstructure of magnetite nanocrystals dispersed in indium-tin oxide thin films.
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DOI：
10.1021/am9003057
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发表时间：
2009-09
影响因子：
9.5
通讯作者：
K. Okada;S. Kohiki;M. Mitome;Hidekazu Tanaka;M. Arai;M. Mito;H. Deguchi
中科院分区：
文献类型：
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作者：
K. Okada;S. Kohiki;M. Mitome;Hidekazu Tanaka;M. Arai;M. Mito;H. Deguchi
以纳米磁性铁氧体(Fe(3)O(4))为靶材，采用脉冲激光沉积技术，在氧化钇稳定的氧化锆(YSZ)衬底上制备了外延氧化铟(ITO)薄膜。在1T磁场下，薄膜的磁阻在45K时为39%，在225K以上保持在3%左右。薄膜在直流磁化强度的温度依赖关系中表现出冷却滞后。透射电子显微镜显示，Fe(3)O(4)相分离的纳米晶在薄膜的衬底上析出并外延生长，其宽度约为40-150 nm，高度约为10-25 nm。Fe(3)O(4)(111)面和ITO(001)面均平行于YSZ(001)面。Fe(3)O(4)(11-2)和-(1-10)晶面分别平行于ITO(100)和-(010)晶面，晶界连接顺畅。用第一性原理电子结构计算得到的Fe(3)O(4)(111)面上的电子密度等值线图与ITO(001)面上的电子密度等值线图相似。[111]取向的Fe(3)O(4)纳米晶对外延ITO薄膜的载流子起着自旋对齐的作用。
Epitaxial indium-tin oxide (ITO) thin films were fabricated on a yttria-stabilized zirconia (YSZ) substrate by pulsed-laser deposition using magnetite (Fe(3)O(4)) nanoparticle dispersed ITO powders as a target. Magnetoresistance of the film at a field of 1 T was 39% at 45 K, and it stayed at 3% above 225 K. The film demonstrated cooling hysteresis in the temperature dependence of direct-current magnetization. Transmission electron microscopy revealed that phase-separated Fe(3)O(4) nanocrystals with widths of approximately 40-150 nm and heights of approximately 10-25 nm precipitated and grew epitaxially on the substrate in the film. Both the Fe(3)O(4)(111) and ITO(001) planes were parallel to the YSZ(001) plane. The Fe(3)O(4)(11-2) and -(1-10) planes were parallel to the ITO(100) and -(010) planes, respectively, and the planes connected smoothly at the grain boundary. The contour map of the electron density for the Fe(3)O(4)(111) plane by the first-principles electronic structure computation was similar to that for the ITO(001) plane. The [111]-oriented Fe(3)O(4) nanocrystals played the role of spin aligner for charge carriers of the epitaxial ITO film.