Tunable positive magnetoresistance effect of Co-doped amorphous carbon films
Tunable positive magnetoresistance effect of Co-doped amorphous carbon films
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DOI：
10.1063/1.3675180
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发表时间：
2012-03
影响因子：
3.2
通讯作者：
Y. C. Jiang;Z. Wu;W. Bao;Shijie Xu;Jin-Hua Gao
中科院分区：
文献类型：
--
作者：
Y. C. Jiang;Z. Wu;W. Bao;Shijie Xu;Jin-Hua Gao
采用脉冲激光沉积法在n型Si衬底上制备了Co掺杂非晶碳（a-C：Co）薄膜。Co掺杂a-C薄膜后，观察到了正的磁电阻效应。从a-C：Co/Si结在不同磁场下的电流-电压关系可以看出，这种PMR由偏置电压调节，并在特定电压处达到峰值。进一步研究了65 K下a-C：Co/Si结的MR-H特性，发现在反向电场作用下，a-C：Co/Si结具有巨大的PMR（超过100%）。拉曼光谱结果表明，Co掺杂有利于石墨sp2位的形成。PMR效应的产生是由于外加磁场与Co离子之间的相互作用，导致薄膜的sp2位向sp3位跃迁，从而增加了薄膜的电阻。
Co-doped amorphous carbon (a-C:Co) films were deposited on n-type Si substrates by pulsed-laser deposition method. A positive magnetoresistance (PMR) effect has been observed after Co doped into a-C films. Such a PMR is tuned by the bias voltage and reaches a peak at a particular voltage, as observed from the Current-voltage relations of the a-C:Co/Si junctions at various magnetic fields. MR-H characteristics were further studied at the temperatures of 65 K, which showed that under the reverse electric field the a-C:Co/Si junctions had a colossal PMR (over 100%). Raman spectra results demonstrate that Co doping favors the formation of graphitic sp2 sites. The mechanism of the PMR effect is attributed to the interactions between the applied magnetic field and Co ions, which leads to the transition from sp2 sites to sp3 sites and increase the resistance.