Pressure‐Driven Intrinsic Quantum Confinement and Semiconducting‐to‐Metallic Transition in the Topological Flat Bands Kagome Nb₃Cl₈ Compounds

Abstract

Abstract Nb 3 Cl 8 is a unique subset of 2D crystalline materials renowned for their Kagome structure and distinctive flat energy bands. These bands contribute to the distinct electronic behavior, rendering Nb 3 Cl 8 a compelling subject for study. In this study, by employing ab initio calculations, the impact of pressure on the electronic properties of Nb 3 Cl 8 is scrutinized, yielding valuable insights. Under high pressures, Nb 3 Cl 8 undergoes a transition from a semiconductor state (with a 1.23 eV bandgap) to a metallic one, accompanied by electronic band restructuration. Notably, the flat energy bands are suppressed with increasing pressure. Furthermore, this investigation underscores the distinctive nature of flat energy bands in Nb 3 Cl 8 , delving into quantum effects, particularly their association with the quantum confinement of electronic states. The confinement of charge carriers in Nb 3 Cl 8 results in discrete energy levels, corresponding to specific orbitals in the density of states, indicating robust electron confinement. Pressure‐induced changes in the energy gap between these quantized levels suggest a decrease in confinement strength. Consequently, the study lays a robust foundation for future exploration, contributing to the development of innovative electronic devices grounded in quantum confinement effects.