Manipulation of band gap in 1T-TiSe_(2) via rubidium deposition  

作　　者：欧仪 陈磊 信子鸣 任宇靖 袁鹏浩 王政国 朱玉 陈景芝 张焱 Yi Ou;Lei Chen;Zi-Ming Xin;Yu-Jing Ren;Peng-Hao Yuan;Zheng-Guo Wang;Yu Zhu;Jing-Zhi Chen;Yan Zhang(International Center for Quantum Materials,School of Physics,Peking University,Beijing 100871,China)

机构地区：[1]International Center for Quantum Materials,School of Physics,Peking University,Beijing 100871,China

出　　处：《Chinese Physics B》2024年第8期102-106,共5页中国物理B（英文版）

基　　金：Project supported by the National Key Research and Development Program of China (Grant Nos.2022YFA1403502 and 2018YFA0305602);the National Natural Science Foundation of China (Grant No.11888101);SSRF is supported by ME2 project under contract No.11227901 from the National Natural Science Foundation of China。

摘　　要：The 1T-TiSe_(2) is a two-dimensional charge-density-wave(CDW)material that attracts great interest.A small band gap locates at the Fermi level separating the Ti d-bands and Se p-bands,which makes 1T-TiSe_(2) a promising candidate for realizing excitonic condensation.Here,we studied the band gap in 1T-TiSe_(2) using angle-resolved photoemission spectroscopy(ARPES).Instead of only focusing on the in-plane band dispersions,we obtained the detailed band dispersions of both conduction and valance bands along the out-of-plane direction.We found that the conduction and valance bands split into multiple sub-bands in the CDW state due to band folding.As a result,the band gap between the Ti d-bands and Se p-bands reduces to~25 meV and becomes a direct gap in the CDW state.More intriguingly,such band gap can be further reduced by the rubidium deposition.The band structure becomes semimetallic in the rubidium-doped sample.Meanwhile,exotic gapless behaviors were observed at the p-d band crossing.Our result characterized the band gap of 1T-TiSe_(2) in three-dimensional Brillouin zone with unpreceded precision.It also suggests a closing of band gap or a potential band inversion in 1T-TiSe_(2) driven by rubidium deposition.

关 键 词：angle-resolved photoemission spectroscopy metal–insulator transition transition metal dichalcogenides 

分 类 号：O413[理学—理论物理]