上海科技大学知识管理系统

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 the quasi-two-dimensional binary rare-earth tetratelluride 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?0.67b? drives the formation of the 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 the appearance of semiconductor properties, (iii) an abnormal behavior of CDW gap in magnitude as a function of temperature, and (iv) an extra, larger gap opens at higher binding energy due to the interaction between the different orbits of the main bands. © 2022 American Physical Society.