中文摘要：

采用磁控共溅射方法在n型Si（100）基片上制备了一系列具有不同Co含量（x,at%）的Co掺杂非晶C颗粒薄膜,溅射温度为室温。研究了Co-C颗粒薄膜的微结构,磁输运特性及磁性能。通过优化Co含量,在低温下发现了较大的负磁电阻（MR）。温度为2K、磁场为90×79.6kA.m-1时,Co含量为6.4at%的Co-C薄膜的负磁电阻值最大,达到27.6%。随着Co含量从6.4at%增加至16.4at%,MR值从27.6%逐渐减小至2.2%。电阻率？？随温度T的变化曲线显示了线性的ln？-T-1/2关系,说明样品中电子传导遵循隧穿输运机制。

英文摘要：

A series of Co-doped amorphous carbon granular thin films with various Co contents（x,at%） were deposited on n-type Si（100） substrates by a magnetron co-sputtering technique at room temperature.The microstructure,magnetotransport and magnetic properties of the Co-C films have been characterized.By optimizing Co content,giant negative magnetoresistances（MRs） were observed at low temperature,with a maximum MR ratio of 27.6% at 2 K under an applied magnetic field of 90×79.6 kA.m-1 for the film with Co content of 6.4 at%.As Co content increases from 6.4 at% to 16.4 at%,the MR ratio decreases gradually from 27.6% to 2.2%.A linear ln？-T-1/2 relationship indicates that the spin transport in Co6.4C93.6 thin film agrees well with tunneling conductance.