Correlated Disorder in van der Waals Heterostructures

TL;DR

This paper investigates the presence and effects of correlated structural disorder in van der Waals heterostructures, revealing how it influences their properties and introduces pseudo-3D behavior despite their layered nature.

Contribution

It uncovers the coexistence of correlated disorder with crystallographic order in vdW heterostructures and demonstrates its impact on their structural and physical characteristics.

Findings

Correlated disorder coexists with crystallographic order in vdW heterostructures.

Correlated disorder induces pseudo-3D behavior in layered systems.

Structural diversity is underpinned by spatially correlated disorder states.

Abstract

The individual building blocks of van der Waals (vdW) heterostructures host fascinating physical phenomena, ranging from ballistic electron transport in graphene to striking optical properties of MoSe2 sheets. The presence of bonded and non-bonded cohesive interactions in a vdW heterostructure, promotes diversity in their structural arrangements, which in turn profoundly modulate the properties of their individual constituents. Here, we report on the presence of correlated structural disorder coexisting with the nearly perfect crystallographic order along the growth direction of epitaxial vdW heterostructures of Bi2Se3/graphene/SiC. Using the depth penetration of X-ray diffraction microscopy and scattering, we probed their crystal structure from atomic to mesoscopic length scales, to reveal that their structural diversity is underpinned by spatially correlated disorder states. The presence of the latter induces on a system, widely considered to behave as a collection of nearly independent 2-dimensional units, a pseudo-3-dimensional character, when subjected to epitaxial constraints and ordered substrate interactions. These findings shed new light on the nature of the vast structural landscape of vdW heterostructures and could enable new avenues in modulating their unique properties by correlated disorder.