【摘要】 石墨是准二维半金属材料 ,然而在通常细晶粒、无取向的石墨中并没有发现很大的磁电阻效应 .在高度取向的石墨中发现了巨大的正磁电阻效应 ,在 8.15T的外磁场中 ,4 2 ,3 0 0K温度下的磁电阻分别高达 853 0 0 %和 4950 % .生产这一巨磁电阻效应的机制除正常磁电阻效应外 ,可能源于磁场诱导的类金属 绝缘体的转变更多还原

【Abstract】 Graphite is a quasi_two_dimensional semimetal. However, for usual graphite the magnetoresistance is not so high due to its small crystal size and no preferred orientation. Huge positive magnetoresistance up to 85300% at 4.2?K and 4950% a t 300?K under 8.15?T magnetic field was found in highly oriented pyrolytic gra phite. The mechanism of huge positive magnetoresistance is not only due to ordin ary magnetoresistan ce but also due to magnetic_field_driven semimetal_insulator transition.更多还原