Charge density waves in the 2.5-dimensional quantum heterostructure

Abstract

Charge density wave (CDW) and their interplay with correlated and topological quantum states are at the forefront of condensed matter research. The 4⁢𝐻𝑏−TaS2 is a CDW ordered quantum heterostructure that is formed by alternative stacking of Mott insulating 1T-TaS2 and Ising superconducting 1H-TaS2. While the √13×√13 and 3×3 CDWs have been respectively observed in the bulk 1T-TaS2 and 2H-TaS2, the CDWs and their pivotal role for unconventional superconductivity in the 4⁢𝐻𝑏−TaS2 remain unsolved. In this Letter, we reveal the two-dimensional (2D) √13×√13 chiral CDW in the 1T layers and intraunit cell coupled 2D 2×2 CDW in the 1H and 1H' layers of 4⁢𝐻𝑏−TaS2. Our results establish 4⁢𝐻𝑏−TaS2 a 2.5D quantum heterostructure, where 2D quantum states emerge from 3D crystalline structure.