Emergent Moir\'e fringes in direct-grown quasicrystal

TL;DR

This paper reports the synthesis of 2D quasicrystals with Moiré patterns formed by twisted graphene layers, revealing new physical phenomena and validating theoretical models of lattice mismatch and relaxation.

Contribution

It demonstrates the first observation of Moiré fringes in direct-grown 2D quasicrystals, linking experimental findings to theoretical predictions about lattice mismatch and stress cancellation.

Findings

Moiré patterns observed in 2D quasicrystals with twist angles.

Moiré periodicity varies with layer parity, matching theory.

Atomic relaxation confirmed via STEM imaging.

Abstract

Quasicrystals represent a category of rarely structured solids that challenge traditional periodicity in crystal materials. Recent advancements in the synthesis of two-dimensional (2D) van der Waals materials have paved the way for exploring the unique physical properties of these systems. Here, we report on the synthesis of 2D quasicrystals featuring 30{\deg} alternating twist angles between multiple graphene layers, using chemical vapor deposition (CVD). Strikingly, we observed periodic Moir\'e patterns in the quasicrystal, a finding that has not been previously reported in traditional alloy-based quasicrystals. The Moir\'e periodicity, varying with the parity of the constituent layers, aligns with the theoretical predictions that suggest a stress cancellation mechanism in force. The emergence of Moir\'e fringes is attributed to the spontaneous mismatched lattice constant in the oriented graphene layers, proving the existence of atomic relaxation. This phenomenon, which has been largely understudied in graphene systems with large twist angles, has now been validated through our use of scanning transmission electron microscopy (STEM). Our CVD-grown Moir\'e quasicrystal provides an ideal platform for exploring the unusual physical properties that arise from Moir\'e periodicity within quasicrystals.