Electronic Correlations in Twisted and Strained Moiré Heterostructures

Since the experimental isolation of graphene in 2004, two-dimensional (2D) materials have been at the forefront of condensed matter physics.

In recent years, a new revolution in the field started from the experimental observation of unconventional superconductivity, and other strongly correlated phases of matter, in superlattices of two stacked graphene layers with a relative twist of about 1 degree.

Similar behaviors have been also observed in twisted double bilayer graphene and twisted trilayer graphene, among others.

As these twist-induced systems give rise to a moiré pattern due to the lattice mismatch created, they are generally labeled as Moiré Heterostructures. So far, the current state-of-the-art encompasses the twist angle as the tune parameter in moiré heterostructures. Not much has been devoted to investigate the strain role as an additional tune parameter.

The strain, when compared to the twist angle, offers a much wider possible forms of moiré patterns because it effectively distorts each layer.

This provides a potentially extremely broad and rich experimental platform to modify the properties of the moiré heterostructures.

Although the strain typically arises naturally and randomly during the fabrication of the samples, recent technological advances have opened the possibility of manipulating to a high precision the strain on each layer.

Within this promising and emergent scenario, this proposal aims to understand the nature of electronic correlations in moiré heterostructures formed by twisted and strained 2D materials.

We will study how the interplay between twist and strain can give rise to moiré patterns with unique electronic properties, such as unconventional superconductivity and other strongly-correlated phases of matter.

From this we will form a solid theoretical foundation from which one can further propose and engineering superlattices configuration with useful potential applications.