Layered tellurides have been extensively studied as a platform for investigating the Fermi surface (FS) nesting-driven charge density wave (CDW) states. EuTe4, one of quasi-two-dimensional (quasi-2D) binary rare-earth tetratellurides CDW compounds, with unconventional hysteretic transition, is currently receiving much attention. Here, the CDW modulation vector, momentum and temperature dependence of CDW gaps in EuTe4 are investigated using angle-resolved photoemission spectroscopy. Our results reveal that (i) a FS nesting vector q ~ 0.67 b* drives the formation of CDW state, (ii) a large anisotropic CDW gap is fully open in the whole FS, and maintains a considerable size even at 300 K, leading to appearance of semiconductor properties, (iii) an abnormal non-monotonic increase of CDW gap in magnitude as a function of temperature, (iv) an extra, larger gap opens at a higher binding energy due to the interaction between the different orbits of the main bands.
@article{arxiv.2203.09206,
title = {Angle-resolved photoemission spectroscopy study of the charge density wave order in layered semiconductor EuTe4},
author = {Chen Zhang and Qi-Yi Wu and Ya-Hua Yuan and Wei Xia and Hao Liu and Zi-Teng Liu and Hong-Yi Zhang and Jiao-Jiao Song and Yin-Zou Zhao and Fan-Ying Wu and Shu-Yu Liu and Bo Chen and Xue-Qing Ye and Sheng-Tao Cui and Zhe Sun and Xiao-Fang Tang and Jun He and Hai-Yun Liu and Yu-Xia Duan and Yan-Feng Guo and Jian-Qiao Meng},
journal= {arXiv preprint arXiv:2203.09206},
year = {2022}
}