# Dimensionality reduction and band quantization induced by potassium intercalation in 1$T$-HfTe$_2$

## TL;DR

This study uses angle-resolved photoemission spectroscopy to investigate how potassium intercalation induces a transition from three-dimensional to two-dimensional electronic states in HfTe$_2$, revealing staging phenomena and band quantization.

## Contribution

It demonstrates a systematic control of electronic dimensionality in HfTe$_2$ through potassium intercalation, highlighting staging and band quantization effects.

## Key findings

- Dimensional crossover from 3D to 2D electronic states due to K intercalation.
- Observation of quantized bands from bilayer and trilayer HfTe$_2$.
- Staging behavior indicating layered electronic structure modulation.

## Abstract

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.