Fe/Si薄膜中相干声学声子的光激发研究

张郑兵; 马小柏; 金钻明; 马国宏; 杨金波

上海大学理学院物理系,上海,200444

北京大学人工微结构和介观物理国家重点实验室,北京,100871

Photoinduced coherent acoustic-phonons in Fe/Si film

摘要: 本文通过抽运一探测技术,利用飞秒激光脉冲激发并探测了Fe/Si薄膜中的高频相干声学声子.通过经典的阻尼谐振函数,对声学声子的动力学行为进行了拟合.实验及拟合结果表明,该声学声子的共振频率约为0.25 THz,其退相时间约为12 ps,且都与激发光的波长和能量密度无关.声学声子的振幅随着激发光能量密度的增加而线性地增强.临界参数12Τe-ph/T约为0.6,表明相干声学声子的驱动力主要来源于电子热应力的贡献.最后,结合薄膜的厚度和质量密度,可以得到室温下垂直于该.Fe/Si薄膜表面（out of plane）的弹性常数C⊥约为283 GPa.

关键词:

Abstract: High frequency coherent acoustic-phonons are excited in Fe/Si film by using femtosecond pump-probe technique. The dynamics of coherent acoustic-phonons can be fitted well to a classical damped harmonic function. The frequency and the dephasing time of the observed acoustic-phonons are 0.25 THz and 12 ps, respectively, which are independent of pumping photo-energy and fluence. Moreover, the amplitude of the coherent acoustic-phonons is linearly proportional to the fluence. The critical parameter （12Te-ph/T） is calculated to be about 0.6, which indicates that the electron pressure might play a significant role in driving coherent acoustic phonons. The thickness and the mass density of the film are required to determine the out-of-plane elastic constant C⊥ 283 GPa of the Fe/Si film.

Fe/Si薄膜中相干声学声子的光激发研究

上海大学理学院物理系,上海,200444

北京大学人工微结构和介观物理国家重点实验室,北京,100871

关键词:

Photoinduced coherent acoustic-phonons in Fe/Si film

上海大学理学院物理系,上海,200444

北京大学人工微结构和介观物理国家重点实验室,北京,100871

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