Shaping van der Waals nanoribbons via torsional constraints: Scrolls, folds and supercoils

TL;DR

This paper introduces a new method to control the formation of scrolls, folds, and supercoils in nanoribbons by applying torsional constraints, with insights from atomistic simulations and experiments on graphene and magnetic films.

Contribution

It demonstrates a novel approach to induce and control specific conformations in nanoribbons through torsional constraints and non-local van der Waals interactions.

Findings

Decreasing end distance induces scrolls and folds in nanoribbons.

Energy partitioning favors soft conformations due to van der Waals interactions.

Conformational phase diagram matches theoretical predictions.

Abstract

Interplay between structure and function in atomically thin crystalline nanoribbons is sensitive to their conformations yet the ability to prescribe them is a formidable challenge. Here, we report a novel paradigm for controlled nucleation and growth of scrolled and folded shapes in finite-length nanoribbons. All-atom computations on graphene nanoribbons (GNRs) and experiments on macroscale magnetic thin films reveal that decreasing the end distance of torsionally constrained ribbons below their contour length leads to formation of these shapes. The energy partitioning between twisted and bent shapes is modified in favor of these densely packed soft conformations due to the non-local van Der Waals interactions in these 2D crystals; they subvert the formation of supercoils that are seen in their natural counterparts such as DNA and filamentous proteins. The conformational phase diagram is in excellent agreement with theoretical predictions. The facile route can be readily extended for tailoring the soft conformations of crystalline nanoscale ribbons, and more general self-interacting filaments