单壁碳纳米管微分电导在高压和强磁场下的实验研究

Study of single-walled carbon nanotube's differential conductance in high magnetic field under high pressure

单壁碳纳米管在高压下会发生结构相变,导致金属型的碳纳米管变成半导体.相变后碳纳米管中电子的库仑关联的表现形式发生变化,从Luttingerliquid行为转变成环境量子涨落行为.同时,相变后电子波函数的相位关联导致弱局域化行为的出现.为了研究库仑关联和相位关联之间是否有相互影响,使用金刚石对顶砧和液压自锁高压包在0—10GPa准静压范围内测量了单层碳纳米管样品在低温和不同磁场下的微分电导随偏压的依赖关系.实验结果表明,相位关联和库仑关联是两种独立的效应,各自影响着电子的输运行为.

Accompanied by the structural phase transition, the electron transport properties of single-walled carbon nanotubes bundles undergo a metal-semiconductor transition at a hydrostatic pressure of 1.5 GPa. In the semiconducting phase there coexist two effects electron phase coherence which leads to two-dimensional electron weak localization, and Coulomb correlation which leads to the environmental quantum fluctuation of charge transport. We applied hydrostatic pressure up to 10 GPa to single-walled carbon nanotube bundles, and studied the bias voltage dependence of the differential conductance at low temperatures and in strong magnetic fields. Our results show that phase coherence and Coulomb correlation are two effects that independently influence on the electron transport process in the semiconducting phase of the single walled carbon nanotube bundles.