基于飞秒激光对PbI_(2)薄膜瞬态克尔磁光效应研究  

Transient Kerrmagneto-optical effect in PbI_(2) thin films by femtosecond laser

作　　者：吴彦文 相广彪 苗晓娜 李雨爽 冷建材[2] 马红[1] WU Yanwen;XIANG Guangbiao;MIAO Xiaona;LI Yushuang;LENG Jiancai;MA Hong(School of Physics and Electronics,Shandong Normal University,Jinan,Shandong 250353,China;School of Electronic and Information Engineering(Department of Physics),Qilu University of Technology(Shandong Academy of Sciences),Jinan,Shandong 250353,China)

机构地区：[1]山东师范大学物理与电子科学学院,山东济南250358 [2]齐鲁工业大学(山东省科学院),电子信息工程学院(大学物理教学部),山东济南250353

出　　处：《光电子．激光》2022年第5期536-542,共7页Journal of Optoelectronics·Laser

基　　金：山东省自然科学基金(ZR2020MA081,ZR2019MA037,ZR2018BA031)资助项目。

摘　　要：本文利用飞秒瞬态反射光谱和克尔旋转光谱,系统研究了溶液法制备的厚度为~200 nm的PbI_(2)薄膜的动力学过程,并讨论了自旋弛豫机制。研究结果表明,瞬态反射光谱在502 nm处出现漂白峰,在487和522 nm处出现吸收峰,分别归因于带填充效应和带隙重整效应。左旋圆偏振光和右旋圆偏振光激发得到的克尔磁光信号符号相反、大小相等,最大克尔旋转角和椭偏率分别达到10°和0.12/μm。自旋弛豫寿命随抽运光通量的增加而缩短,最短弛豫寿命为1.6 ps,自旋弛豫机制归因于强自旋轨道耦合效应导致的Elliott-Yafet机制。另外,结果发现克尔磁光效应在带隙附近信号较强。在测量的波长范围内,自旋弛豫寿命均在几个皮秒量级,表明了PbI_(2)材料是制备自旋电子器件的良好材料,并且在带隙附近灵敏度最高。The carrier and spin dynamics in solution-processed PbI_(2) film on quartz substrate have been systematically studied by transient reflectance(TR) spectroscopy and femtosecond resolved Kerr rotation spectroscopy.The results show that TR spectroscopy includes one band of photo-induced bleach(PB) centered at 502 nm and two bands of photo-induced absorption(PIA) at 487 and 522 nm,which are interpreted by band filling effect and band gap renormalization effect.The Kerr magneto-optical signals excited by left-handed and right-handed circularly polarized light are completely opposite in sign and almost equal in size.With the increase of pump fluence,the Kerr rotation angle and ellipticity increase linearly at first,then slowly,finally reach maximum value,~10 degree and 0.12 per micro,respectively.At the same time,the spin relaxation life decreases a minimum value ~1.6 ps.According to our experimental data,the spin relaxation mechanism in PbI_(2) thin films is attributed to the Elliott-Yafet process owing to the strong spin-orbit coupling caused by the heavy atom lead.In addition,we find that Kerr effect has a large signal around the band gap,which suggests that the spintronic devices based on PbI_(2) have high sensitivity around the band gap.These experimental results obtained in this paper are of great significance for exploring the potential applications of PbI_(2) thin films in spintronic devices.

关 键 词：PbI_(2)薄膜 瞬态反射光谱 克尔旋转光谱 自旋弛豫寿命 

分 类 号：O433[机械工程—光学工程]