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Register a new userDimensionality reduction and band quantization induced by potassium intercalation in 1$T$-HfTe$_2$
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We have performed angle-resolved photoemission spectroscopy on transition-metal dichalcogenide 1$T$-HfTe$_2$ to elucidate the evolution of electronic states upon potassium (K) deposition. In pristine HfTe$_2$, an in-plane hole pocket and electron pockets are observed at the Brillouin-zone center and corner, respectively, indicating the semimetallic nature of bulk HfTe$_2$, with dispersion perpendicular to the plane. In contrast, the band structure of heavily K-dosed HfTe$_2$ is obviously different from that of bulk, and resembles the band structure calculated for monolayer HfTe$_2$. It was also observed that lightly K-dosed HfTe$_2$ is characterized by quantized bands originating from bilayer and trilayer HfTe$_2$, 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.
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By using angle-resolved photoemission spectroscopy (ARPES), the variation of the electronic structure of HfSe$_2$ has been studied as a function of sodium intercalation. We observe how this drives a band splitting of the p-orbital valence bands and a simultaneous reduction of the indirect band gap by values of up to 400 and 280 meV respectively. Our calculations indicate that such behaviour is driven by the band deformation potential, which is a result of our observed anisotropic strain induced by sodium intercalation. The applied uniaxial strain calculations based on density functional theory (DFT) agree strongly with the experimental ARPES data. These findings should assist in studying the physical relationship between doping and strain, as well as for large-scale two-dimensional straintronics.
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