Anisotropic Strain Induced Soliton Movement Changes Stacking Order and Bandstructure of Graphene Multilayers

TL;DR

This study explores how anisotropic strain influences soliton movement, stacking order, and electronic properties in multilayer graphene, revealing methods to control and reliably contact different stacking configurations.

Contribution

It demonstrates that mechanical strain can move solitons and alter stacking order in multilayer graphene, providing strategies for stable electrical contact to different configurations.

Findings

Strain can move solitons by several micrometers in graphene.

Dry transfer can induce stacking transformations.

Density functional theory confirms decreased rhombohedral stability under anisotropic deformation.

Abstract

The crystal structure of solid-state matter greatly affects its electronic properties. For example in multilayer graphene, precise knowledge of the lateral layer arrangement is crucial, since the most stable configurations, Bernal and rhombohedral stacking, exhibit very different electronic properties. Nevertheless, both stacking orders can coexist within one flake, separated by a strain soliton that can host topologically protected states. Clearly, accessing the transport properties of the two stackings and the soliton is of high interest. However, the stacking orders can transform into one another and therefore, the seemingly trivial question how reliable electrical contact can be made to either stacking order can a priori not be answered easily. Here, we show that manufacturing metal contacts to multilayer graphene can move solitons by several $\mu$m, unidirectionally enlarging Bernal domains due to arising mechanical strain. Furthermore, we also find that during dry transfer of multilayer graphene onto hexagonal Boron Nitride, such a transformation can happen. Using density functional theory modeling, we corroborate that anisotropic deformations of the multilayer graphene lattice decrease the rhombohedral stacking stability. Finally, we have devised systematics to avoid soliton movement, and how to reliably realize contacts to both stacking configurations.