飞秒激光诱发Ni及其异质结薄膜的太赫兹辐射测量  

Measuring terahertz radiation from Ni and its heterojunction thin films by femtosecond laser

作　　者：卫翼 方铄 李恒一 WEI Yi;FANG Shuo;LI Hengyi(College of Chemistry and Material Science,University of Science and Technology of China,Hefei 230026,China;College of Physical Science,University of Science and Technology of China,Hefei 230026,China)

机构地区：[1]中国科学技术大学化学与材料科学学院,安徽合肥230026 [2]中国科学技术大学物理学院,安徽合肥230026

出　　处：《物理实验》2024年第12期40-45,共6页Physics Experimentation

基　　金：中国科学技术大学校级教学研究项目(No.2023xjyxm071)。

摘　　要：采用磁控溅射法在SiO_(2)基底上生长厚度均为10 nm的Ni膜、Ni/Pt和CoFeB/Ni双层异质结薄膜,并测量3种薄膜在飞秒脉冲激光激发下的太赫兹发射谱.通过频谱分析发现,这3种Ni薄膜的太赫兹辐射主要来源于超快自旋-电荷的转换,且不同结构的转换机制不同.对于单层Ni薄膜,太赫兹辐射主要来源于Ni的超快退磁和异常霍尔效应;对于Ni/Pt双层膜,此时Ni起自旋注入作用,由Pt完成自旋-电荷转换而产生太赫兹信号;对于CoFeB/Ni双层膜,自旋电流由CoFeB产生,而Ni起自旋-电荷转换作用.通过飞秒激光-太赫兹技术,可以研究铁磁Ni材料的磁学特性.Ni film,Ni/Pt bilayer and CoFeB/Ni bilayer heterojunction with a thickness of 10 nm were grown on SiO_(2)substrates by magnetron sputtering,and their terahertz emission spectra excited by femtosecond laser technology were measured.Through spectral analysis,it was found that the terahertz radiation of these three kinds of Ni films mainly came from the ultrafast spin-to-charge conversion,and the conversion mechanism was different for different structures.For single-layer Ni films,terahertz radiation was mainly due to the ultrafast demagnetization of Ni and the anomalous Hall effect.For the Ni/Pt bilayer,Ni played the role of spin injection,and the Pt completed the spin-to-charge conversion to generate a terahertz signal.For CoFeB/Ni bilayer,the spin current was generated by CoFeB,and Ni played the role of spin-to-charge conversion.The magnetic properties of ferromagnetic Ni materials could be studied by the femtosecond laser-terahertz technology.

关 键 词：Ni薄膜 异质结薄膜 飞秒激光技术 太赫兹发射谱 自旋-电荷转换 

分 类 号：O43[机械工程—光学工程]