Charge Density Waves in the 2.5-Dimensional Quantum Heterostructure

TL;DR

This paper uncovers complex charge density wave patterns in a layered quantum heterostructure, revealing how 2D quantum states emerge from a 3D crystal, advancing understanding of CDWs in novel materials.

Contribution

It demonstrates the presence of specific 2D charge density waves in 4H_b-TaS2, establishing it as a unique 2.5D quantum heterostructure with emergent quantum states.

Findings

Identification of 2D $\sqrt{13} imes\sqrt{13}$ chiral CDW in 1T layers

Observation of intra-unit cell coupled 2D 2$ imes$2 CDW in 1H and 1H' layers

Establishment of 4H_b-TaS2 as a novel 2.5D quantum heterostructure

Abstract

Charge density wave (CDW) and their interplay with correlated and topological quantum states are forefront of condensed matter research. The 4$H_{b}$-TaS$_2$ is a CDW ordered quantum heterostructure that is formed by alternative stacking of Mott insulating 1T-TaS$_2$ and Ising superconducting 1H-TaS$_2$. While the $\sqrt{13}\times\sqrt{13}$ and 3$\times$3 CDWs have been respectively observed in the bulk 1T-TaS$_2$ and 2H-TaS$_2$, the CDWs and their pivotal role for unconventional superconductivity in the 4$H_{b}$-TaS$_2$ remain unsolved. In this letter, we reveal the 2-dimensional (2D) $\sqrt{13}\times\sqrt{13}$ chiral CDW in the 1T-layers and intra-unit cell coupled 2D 2$\times$2 CDW in the 1H and 1H' layers of 4$H_{b}$-TaS$_2$. Our results establish 4$H_{b}$-TaS$_2$ a novel 2.5D quantum heterostructure, where 2D quantum states emerge from 3D crystalline structure.