Fe/Si薄膜中相干声学声子的光激发研究  

Photoinduced coherent acoustic-phonons in Fe/Si film

作　　者：张郑兵[1] 马小柏[2] 金钻明[1] 马国宏[1] 杨金波[2] 

机构地区：[1]上海大学理学院物理系,上海200444 [2]北京大学人工微结构和介观物理国家重点实验室,北京100871

出　　处：《物理学报》2012年第9期414-418,共5页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11174195;50701003);上海市科学技术委员会基础研究计划(批准号:09530501100);上海市重点学科建设基金(批准号:S30105);国家重点基础研究发展计划(973计划)(批准号:2010CB833104)资助的课题~~

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12_Τe-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.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.

关 键 词：相干声学声子 飞秒抽运-探测技术 Fe/Si薄膜 弹性常数 

分 类 号：O484[理学—固体物理]