Collective excitations and quantum size effects on the surfaces of Pb(111)films:An experimental study  

作　　者：Yade Wang Zijian Lin Siwei Xue Jiade Li Yi Li Xuetao Zhu Jiandong Guo 王亚德;林子荐;薛思玮;李佳德;李毅;朱学涛;郭建东(Beijing National Laboratory for Condensed Matter Physics and Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China;School of Physical Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;Songshan Lake Materials Laboratory,Dongguan 523808,China)

机构地区：[1]Beijing National Laboratory for Condensed Matter Physics and Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China [2]School of Physical Sciences,University of Chinese Academy of Sciences,Beijing 100049,China [3]Songshan Lake Materials Laboratory,Dongguan 523808,China

出　　处：《Chinese Physics B》2021年第7期74-82,共9页中国物理B（英文版）

基　　金：the National Natural Science Foundation of China(Grant Nos.11874404 and 11634016);the National Key Research and Development Program of China(Grant Nos.2016YFA0302400,2016YFA0202300,and 2017YFA0303600);the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB33000000);supported by the Youth Innovation Promotion Association of Chinese Academy of Sciences。

摘　　要：Pb(111)film is a special system that exhibits strong quantum size effects in many electronic properties.The collective excitations,i.e.,plasmons,in Pb(111)films are also expected to show signatures of the quantum size effect.Here,using high-resolution electron energy loss spectroscopy,we measured the plasmons on the surface of Pb(111)films with different film thicknesses and analyzed the plasmon dispersions.One surface plasmon branch exhibits prominent damping in the small momentum range,which can be attributed to the interaction between the top and bottom interfaces of the Pb(111)films.With the film thickness increasing,the critical momentum characterizing the damping in Pb(111)films decays not only much slower in Pb(111)films than in other metal films,and even in films with the thickness up to 40 monolayers the damping still exists.The slow decay of the surface plasmon damping,manifesting the strong quantum size effect in Pb(111)films,might be related to the strong nesting of the Fermi surface along the(111)direction.

关 键 词：Pb films PLASMONS quantum size effects high-resolution electron energy loss spectroscopy 

分 类 号：O484.4[理学—固体物理]