Low field intergranular tunneling effect in CrO2 nanoparticles and characterization of the barriers
Low field intergranular tunneling effect in CrO2 nanoparticles and characterization of the barriers
复制标题
CrO2 纳米粒子的低场晶间隧道效应及势垒表征
DOI：
10.1063/1.1362641
复制
发表时间：
2001
影响因子：
3.2
通讯作者：
Jinke Tang
中科院分区：
文献类型：
--
作者：
J. Dai;Jinke Tang
研究了半金属二氧化铬纳米颗粒体系的磁阻和微观结构。采用场定向的方法，将针状的二氧化铬单畴颗粒定向排列。在矫顽力场下，该结构的磁结表现为两个分离良好的磁结峰，在1000 Oe左右的较低场下，排列的cr2粒子的磁结率达到了bb0 41%。从自旋相关隧道效应的角度分析了二氧化钛纳米颗粒间的磁输运机制。利用透射电镜、x射线衍射和x射线光电子能谱技术，表征了晶间隧道势垒是CrO2颗粒之间非常薄的Cr2O3界面层。研究了冷压二氧化钛纳米粉体磁流变学和电导率的温度依赖性。磁流变率随温度的升高而显著降低，认为与自旋无关的跳变传导是抑制磁流变率的主要原因。
The magnetoresistance (MR) and microstructures of half-metallic CrO2 nanoparticle systems were studied. Using field alignment, the needle-shaped CrO2 single domain particles were aligned in the same orientation. The MR of this structure showed a magnetic junction-like behavior with two well-separated peaks in the MR at coercivity fields and the MR of the aligned CrO2 particles reached >41% at a relatively low field of about 1000 Oe. The magnetotransport mechanism was analyzed in terms of spin dependent tunneling between CrO2 nanoparticles. Using transmission electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy techniques, the intergranular tunneling barrier was characterized to be a very thin Cr2O3 interface layer between the CrO2 particles. Temperature dependence of MR and conductivity in cold-pressed CrO2 nanopowders were studied. The MR significantly decreased with increasing temperature and the spin independent hopping conduction is suggested to be responsible for the suppressi...