Coexistence of percolative and quantum-confined charge orders in marginally twisted TiSe₂/NbSe₂ heterostructure.

Abstract

In homo- or hetero-interface of two dimensional materials, beyond the rigid moiré patterns, the marginal twisting ensures local commensurate stacking registry via reconstruction and thus introduces versatile structural subtleties into the many-body interplay, enabling the coexistence and tessellation of multiple domain-specific emergent states. In this work, we demonstrate that monolayer 1T-TiSe₂ epitaxially grown on 2H-NbSe₂ undergoes spontaneous moiré reconstruction, therein developing distinct charge density wave configurations dictated by stacking orientation. In parallel-stacked regions, the native 2×2 charge order of TiSe₂ persists but experiences domain-selective modulation. Antiparallel-stacked systems host distinctive <math xmlns="http://www.w3.org/1998/Math/MathML"><msqrt><mrow><mn>3</mn></mrow></msqrt><mo>×</mo><msqrt><mrow><mn>3</mn></mrow></msqrt></math> and 2×1 charge orders which exhibit intertwined phenomena unveiled by scanning tunneling microscopy-including bias-toggled negative differential conductance, competitive inter-order penetration, and defect-mediated local ordering reconstitution. These observations coalesce into a unified paradigm, where the <math xmlns="http://www.w3.org/1998/Math/MathML"><msqrt><mrow><mn>3</mn></mrow></msqrt><mo>×</mo><msqrt><mrow><mn>3</mn></mrow></msqrt></math> charge order is quantum confined and isolated in single domain, while the 2×1 charge order permeates across domains, forming a percolative network. Our results demonstrate that the marginal-twist moiré reconstruction is a designer platform to generate rich emergent charge density wave landscapes, which also serves as a nanoscale testbed to decipher their disparate microscopic nature.