Tunable Van Hove Singularity without Structural Instability in Kagome Metal <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>CsTi</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi>Bi</mml:mi></mml:mrow><mml:mrow><mml:mn>5</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>
Bo Liu, Min-Quan Kuang, Yang Luo, Yongkai Li, Cheng Hu, Jiarui Liu, Qian Xiao, Xiquan Zheng, Linwei Huai, Shuting Peng, Zhiyuan Wei, Jianchang Shen, Bingqian Wang, Yu Miao, Xiupeng Sun, Zhipeng Ou, Shengtao Cui, Zhe Sun, Makoto Hashimoto, Dong-Hui Lu, Chris Jozwiak, Aaron Bostwick, Eli Rotenberg, Luca Moreschini, Alessandra Lanzara, Yao Wang, Y. Y. Peng, Yugui Yao, Zhiwei Wang, Jun-Feng He
Abstract
In kagome metal ${\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}$, multiple intertwined orders are accompanied by both electronic and structural instabilities. These exotic orders have attracted much recent attention, but their origins remain elusive. The newly discovered ${\mathrm{CsTi}}_{3}{\mathrm{Bi}}_{5}$ is a Ti-based kagome metal to parallel ${\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}$. Here, we report angle-resolved photoemission experiments and first-principles calculations on pristine and Cs-doped ${\mathrm{CsTi}}_{3}{\mathrm{Bi}}_{5}$ samples. Our results reveal that the van Hove singularity (vHS) in ${\mathrm{CsTi}}_{3}{\mathrm{Bi}}_{5}$ can be tuned in a large energy range without structural instability, different from that in ${\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}$. As such, ${\mathrm{CsTi}}_{3}{\mathrm{Bi}}_{5}$ provides a complementary platform to disentangle and investigate the electronic instability with a tunable vHS in kagome metals.