Atomic frustration-based twistronics

TL;DR

This paper explores atomic frustrated states in twisted bilayer graphene molecules, revealing nonlocal correlations and zero modes that can be engineered through gate voltages, offering new avenues in twistronics.

Contribution

It introduces the concept of atomic frustration in molecular states within twisted bilayer graphene, highlighting the role of broken inversion symmetry and gate tuning in creating novel molecular bindings.

Findings

Atomic frustrated states exhibit nonlocal correlations.

Molecular zero modes appear at the Fermi energy.

Gate voltages can collapse molecular peaks into a single state.

Abstract

We theoretically investigate atomic frustrated states in diatomic molecules hosted by the bilayer graphene setup twisted by the first magic angle and with broken inversion symmetry in the Dirac cones of the system mini Brillouin zones. Such states show local spectral features typically from uncoupled atoms, but counterintuitively, they also exhibit nonlocal molecular correlations, which turn them into atomically frustrated. By considering a particle-hole symmetric molecule in the Moir\'e superlattice length-scale, we reveal distinctly from the metallic Weyl counterparts, a molecular zero mode atomically frustrated at the spectral densities of the dimer's atoms. To this end, a strong metallic phase with a plateau in the density of states established by the broken inversion symmetry, together with pronounced blue and red shifts in the molecular levels, due to the magic angle condition, should occur synergistically with atomic Coulomb correlations. Consequently, an entire collapse of these molecular peaks into a single one atomically frustrated, taking place exactly at the Fermi energy, becomes feasible just by tuning properly opposite gate voltages attached to the graphene monolayers. Therefore, we propose that unusual molecular bindings can be engineered via the twistronics of the bilayer graphene system, in particular, if its metallic phase is fully established.