We have performed angle-resolved photoemission spectroscopy on transition-metal dichalcogenide 1T-HfTe2 to elucidate the evolution of electronic states upon potassium (K) deposition. In pristine HfTe2, an in-plane hole pocket and electron pockets are observed at the Brillouin-zone center and corner, respectively, indicating the semimetallic nature of bulk HfTe2, with dispersion perpendicular to the plane. In contrast, the band structure of heavily K-dosed HfTe2 is obviously different from that of bulk, and resembles the band structure calculated for monolayer HfTe2. It was also observed that lightly K-dosed HfTe2 is characterized by quantized bands originating from bilayer and trilayer HfTe2, indicative of staging. The results suggest that the dimensionality-crossover from 3D (dimensional) to 2D electronic states due to systematic K intercalation takes place via staging in a single sample. The study provides a new strategy for controlling the dimensionality and functionality of novel quantum materials.
@article{arxiv.1907.04962,
title = {Dimensionality reduction and band quantization induced by potassium intercalation in 1$T$-HfTe$_2$},
author = {Y. Nakata and K. Sugawara and A. Chainani and K. Yamauchi and K. Nakayama and S. Souma and P. -Y. Chuang and C. -M. Cheng and T. Oguchi and K. Ueno and T. Takahashi and T. Sato},
journal= {arXiv preprint arXiv:1907.04962},
year = {2019}
}