论文标题
铁膜中厚度依赖性电子动量松弛时间
Thickness-dependent electron momentum relaxation times in iron films
论文作者
论文摘要
2至100 nm厚的铁膜中的Terahertz时域电导率测量解决了施加的电场和产生电流之间的飞秒时间延迟。当前的响应时间从最厚的膜的29 fs减少到最薄的膜的7 fs。宏观响应时间与电导率不符。这不包括所有传导电子的单个松弛时间通用。我们必须假设微观动量松弛时间的分布。宏观响应时间取决于该分布的平均值和变化。响应时间和电导率缩放之间观察到的偏差对应于变异的缩放。微观弛豫时间的变化取决于膜厚度，因为具有不同弛豫时间的电子受到不同的影响，因为它们具有不同的平均自由路径。
Terahertz time-domain conductivity measurements in 2 to 100 nm thick iron films resolve the femtosecond time delay between applied electric fields and resulting currents. This current response time decreases from 29 fs for thickest films to 7 fs for the thinnest films. The macroscopic response time is not strictly proportional to the conductivity. This excludes the existence of a single relaxation time universal for all conduction electrons. We must assume a distribution of microscopic momentum relaxation times. The macroscopic response time depends on average and variation of this distribution; the observed deviation between response time and conductivity scaling corresponds to the scaling of the variation. The variation of microscopic relaxation times depends on film thickness because electrons with different relaxation times are affected differently by the confinement since they have different mean free paths.
