Large magnetoresistance observed in facing-target sputtered Ni-doped CNx amorphous composite films
Large magnetoresistance observed in facing-target sputtered Ni-doped CNx amorphous composite films
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DOI：
10.1016/j.actamat.2007.02.004
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发表时间：
2007-06
期刊：
影响因子：
9.4
通讯作者：
X. -. Wang;W. Mi;E. Jiang;H. Bai
中科院分区：
文献类型：
--
作者：
X. -. Wang;W. Mi;E. Jiang;H. Bai
采用对靶溅射方法在不同氮气分压(Pn)下制备了一系列非晶态Ni掺杂∼23at.%Ni的CNx薄膜。薄膜由镶嵌在CNx基质中的1-4 nm的∼富Ni颗粒组成，在低温下由铁磁性转变为室温下的超顺磁性。当PN值为4%，温度为3K时，最大负磁电阻(MR=[R(H)−R(0)]/R(0))达到−59%。当PN值从4%下降到0%时，电输运机制由隧穿转变为变程跳跃，最大磁阻从∼的59%下降到∼的3.8%。所有薄膜的MR-H曲线在高场区呈现微弱的饱和趋势，在20K以下的MR-T曲线符合LOG|MR|∝−T关系，尽管输运机制不同。大磁阻(−59%)的产生可以归因于自旋相关的高阶隧穿过程。
A series of amorphous Ni-doped CNxfilms with ∼23at.% Ni were fabricated using facing-target sputtering at different nitrogen partial pressures (PN). The films were composed of ∼1–4nm Ni-rich particles embedded in a CNxmatrix and turn from ferromagnetic at low temperatures to superparamagnetic at room temperature. The largest negative magnetoresistance (MR=[R(H)−R(0)]/R(0)) reaches −59% at a PNof 4% and a temperature of 3K. With a decrease of PNfrom 4% to 0%, the electrical transport mechanism changes from tunneling to variable-range hopping and the maximum MR drops from ∼59% to ∼3.8%. The MR–H curves show a weak saturation trend in a high-field regime and the MR–T curves follow the relation of log|MR|∝−T below 20K for all the films, despite the difference in transport mechanism. The origin of the large MR (−59%) can be ascribed to a spin-related high-order tunneling process.