Electronic properties of twisted multilayer graphene

Abstract

Twisted bilayer graphene displays many fascinating properties that can be tuned by varying the relative angle (also called twist angle) between its monolayers. As a remarkable feature, both the electronic flat bands and the corresponding strong electron localization have been obtained at a specific "magic" angle (∼ 1.1 • ), leading to the observation of several strongly correlated electronic phenomena. Such a discovery has hence inspired the creation of a novel research field called twistronics, i.e., aiming to explore novel physical properties in vertically stacked 2D structures when tuning the twist angle between the related layers. In this paper, a comprehensive and systematic study related to the electronic properties of twisted multilayer graphene (TMG) is presented based on atomistic calculations. The dependence of both the global and the local electronic quantities on the twist angle and on the stacking configuration are analyzed, fully taking into account atomic reconstruction effects. Consequently, the correlation between structural and electronic properties are clarified, thereby highlighting the shared characteristics and differences between various TMG systems as well as providing a comprehensive and essential overview. On the basis of these investigations, possibilities to tune the electronic properties are discussed, allowing for further developments in the field of twistronics.

Electronic structure of lattice relaxed alternating twist tNG-multilayer graphene: from few layers to bulk AT-graphite

“…starting from the Wannier representation Blochband Hamiltonian H XX ′ (K : d(r i )) = j t inter ij e iK•r ij [16,17] where X ( ′) is A or B sublattice of bottom(top) layer and the interlayer hopping parameter t inter ij is defined in equation (9). The integration runs over a moire commensurate cell of area A M , and we include both in-plane(u) and out-of-plane(h) stacking deformation d(r) = d 0 (r) + u(r) + h(r)ẑ where d 0 (r) is the rigid relative stacking information [18].…”

“…Twisted graphene systems have emerged as the prime target and candidate for finding correlated electronic phenomena in 2D materials including flat band superconductivity [1][2][3][4][5][6]. Research has expanded beyond the initial investigation of twisted bilayer graphene (t2G) [1] to include a variety of other layered moire materials that have shown hints of similar physics [7][8][9]. Alternating twist N-layer graphene (tNG) systems are particularly interesting for exploring correlation physics in light of recent experiments that have revealed flat band superconductivity for N = 3, 4, 5 systems [3,10,11].…”

Electronic structure of lattice relaxed alternating twist tNG-multilayer graphene: from few layers to bulk AT-graphite

“…Twisted graphene systems have emerged as the prime target and candidate for finding correlated electronic phenomena in 2D materials including flat band superconductivity [1,2,3,4,5,6]. Research has expanded beyond the initial investigation of twisted bilayer graphene (t2G) [1] to include a variety of other layered moire materials that have shown hints of similar physics [7,8,9]. Alternating twist 𝑁layer graphene (t𝑁G) systems are particularly interesting for exploring correlation physics in light of recent experiments that have revealed flat band superconductivity for 𝑁 = 3, 4, 5 systems [10,3,11].…”