Tunable Lifshitz Transitions and Multiband Transport in Tetralayer Graphene

Abstract

As the Fermi level and band structure of two-dimensional materials are readily tunable, they constitute an ideal platform for exploring the Lifshitz transition, a change in the topology of a material's Fermi surface. Using tetralayer graphene that host two intersecting massive Dirac bands, we demonstrate multiple Lifshitz transitions and multiband transport, which manifest as a nonmonotonic dependence of conductivity on the charge density n and out-of-plane electric field D, anomalous quantum Hall sequences and Landau level crossings that evolve with n, D, and B.

Tunable van Hove singularities and correlated states in twisted monolayer–bilayer graphene

“…Similar correlated states have also been reported in ABC-trilayer graphene (TLG) superlattice on hexagonal boron nitride (hBN) and rhombohedral stacked graphite films [12][13][14] .In this work, we study small-angle twisted trilayer graphene (tTLG) van der Waals heterostructures, where a monolayer graphene (MLG) and bilayer graphene (BLG) are stacked and rotated by a small angle with respect to each other. Compared to tBLG, more tuning knobs are expected in tTLG, since the band structures in multi-layer graphene are more tunable than that of the monolayer counterpart [15][16][17][18] . In particular, there naturally exists two stacking orders in trilayer graphene, Bernal (ABA)-stacking with mirror symmetry and rhombohedral (ABC)-stacking with inversion symmetry.…”

Intrinsic resistance peaks in AB-stacked multilayer graphene with odd number of layers

“…Moreover, while the low-energy band structure, which affects transport phenomena, has not been fully revealed by optical measurements, the advent of techniques for making high-quality graphene samples has made it possible to probe the low-energy band structure by using Shubnikov-de Haas oscillations [4,[25][26][27][28][29][30][31][32][33][34][35].…”

“…Recently, high-quality multilayer graphene was found to show intrinsic resistance peaks in its carrier density dependence [31,33,36]. Detailed measurements using graphene samples with top and bottom gate electrodes have uncovered intrinsic resistance ridges structure specific to the band structure of AB-stacked 4-layer [31,33] and 6-layer graphene [36]. These intrinsic resistance ridges are considered to be a promising means of probing the band structure of two-dimensional materials.…”

“…These intrinsic resistance ridges are considered to be a promising means of probing the band structure of two-dimensional materials. The ridges (or peaks) are related to the topological changes in the Fermi surface [31]; the complicated dispersion relations of multilayer graphene are tunable with a perpendicular electric field, and the resultant shape of the Fermi surface (energy contour of the dispersion relations) varies depending on the chemical potential. The ridges in AB-stacked graphene with even number of layers graphene are principally due to two reasons [33,36].…”

“…Conspicuous split ridges appear on the map of resistivity as a function of carrier density and perpendicular electric flux density. The other reason is formation of mini-Dirac cones [41], which are created by the perpendicular electric field [31,33,36]. Trigonal warping locally closes the energy gap created by the perpendicular electric field, and thereby, mini-Dirac cones are created.…”