Preserving Twist-Angle in Marginally Twisted Double-Bilayer Graphene Devices During Fabrication

TL;DR

This paper introduces a fabrication method that preserves the twist-angle in marginally twisted double-bilayer graphene devices, enabling more reliable studies of twist-angle-dependent electronic phenomena.

Contribution

A novel fabrication approach that maintains the twist-angle in mTDBG devices, verified through near-field optical microscopy imaging of the superlattice structure.

Findings

Successful preservation of twist-angle during fabrication.

Direct imaging of the superlattice periodicity.

Enhanced reliability for studying twist-angle physics.

Abstract

Twisted van der Waals heterostructures provide a platform for studying a wide range of electron correlation phenomena, including unconventional superconductivity and correlated insulating states. However, fabricating such devices is challenging due to the difficulty in achieving and maintaining homogeneous twist-angles. Here, we present a fabrication method to preserve the twist-angle with minimal deformation. We fabricated marginally twisted double-bilayer graphene (mTDBG) stacks and directly imaged the resulting triangular superlattice periodicity via scattering-type scanning near-field optical microscopy (s-SNOM). This technique enabled us to monitor twist-angle deformation at each fabrication step, paving the way for more reliable device fabrication and facilitating the exploration of twist-angle-dependent physics.