Observation of square-like moire lattice and quasicrystalline order in twisted rock-salt nitrides

TL;DR

This study demonstrates the fabrication of twisted bilayer transition metal nitrides, revealing square-like moire lattices and quasicrystalline order, which could lead to new quantum states and emergent phenomena in nitride heterostructures.

Contribution

It introduces a generalizable method to create twisted bilayer nitrides with well-defined moire patterns and uncovers novel square and quasicrystalline lattice orders.

Findings

Well-defined square moire superlattices observed

Localized octagonal quasicrystalline order identified

Potential for exploring moire-induced phenomena in nitrides

Abstract

Twistronics, which exploits moire modulation of lattice and electronic structures in twisted bilayers, has emerged as a powerful approach to engineer novel quantum states. Recent efforts have expanded beyond two dimensional van der Waals (vdWs) crystals to more complex, strongly correlated materials, where interfacial moire effects can dominate physical properties. Here we demonstrate a generalizable route to fabricate twisted bilayers of transition metal nitrides with vdWs like interfaces, using freestanding CrN membranes as a model system. Twisted bilayer CrN (tCrN) is realized by employing cubic alkaline earth metal monoxides as sacrificial layers, enabling the assembly of clean, controllable interfaces. Electron ptychography reveals well defined, periodic square moire superlattices in tCrN. For a twist angle of 16.3 degree, we identify a nearly commensurate moire lattice with coincident Cr columns, whereas at 45 degree we uncover localized octagonal quasicrystalline order with clear self-similarity. These results establish a practical platform for twisted TMNs and open avenues to explore moire-induced atomic configurations and emergent correlated phenomena in nitride based heterostructures.