Synergistic correlated states and nontrivial topology in coupled graphene-insulator heterostructures

Abstract

Graphene has aroused great attention due to the intriguing properties associated with its low-energy Dirac Hamiltonian. When graphene is coupled with a correlated insulating substrate, electronic states that cannot be revealed in either individual layer may emerge in a synergistic manner. Here, we theoretically study the correlated and topological states in Coulomb-coupled and gate-tunable graphene-insulator heterostructures. By electrostatically aligning the electronic bands, charge carriers transferred between graphene and the insulator can yield a long-wavelength electronic crystal at the interface, exerting a superlattice Coulomb potential on graphene and generating topologically nontrivial subbands. This coupling can further boost electron-electron interaction effects in graphene, leading to a spontaneous bandgap formation at the Dirac point and interaction-enhanced Fermi velocity. Reciprocally, the electronic crystal at the interface is substantially stabilized with the help of cooperative interlayer Coulomb coupling. We propose a number of substrate candidates for graphene to experimentally demonstrate these effects.

Van der Waals polarity-engineered 3D integration of 2D complementary logic

“…It indicates a cooperative effect of gate-tunable band alignment, charge transfer and e – e interactions, which could essentially be different from conventional p-doping strategies for semiconducting TMDs. It is worthwhile noting that a similar mechanism already leads to a number of exotic quantum electronic states reported previously in graphene–CrOCl systems 41 , 42 . FETs fabricated based on this approach exhibit excellent electrical properties with on/off ratios reaching 10 6 , and the extracted room-temperature hole mobility reaches 425 cm 2 V −1 s −1 in MoS 2 with outstanding long-term air stability.…”

“…Therefore, it is essential to identify an effective approach to achieve p-doped 2D semiconductors without compromising the carrier mobility. Recent research shows that CrOCl is one of the candidates for engineering the interfacial coupling in 2D electronic gas systems such as graphene, which gives rise to exotic quantum ground states 41 , 42 . The interfacial coupling between TMDs and CrOCl, however, remains unexplored so far.…”

Efficient Charge Transfer in Graphene/CrOCl Heterostructures by van der Waals Interfacial Coupling

“…Another possible reason is the screening effect due to interfacial charge transfer in the graphene/CrOCl heterostructure. As described in detail in previous experimental and theoretical investigations, 41,47 by electrostatically aligning the electronic bands, charge carriers transferred between graphene and CrOCl can yield a long-wavelength electronic crystal at the interface. Such a unique interfacial charge coupling may also effectively screen electrostatic gating.…”

“…These findings pave the way for future engineering of exotic quantum electronic states in graphene-based vdW heterostructures by interfacial charge coupling. 47 Yet, the understanding of quantitative charge transfer and interlayer coupling strength of the interaction in graphene/CrOCl heterostructures has not been addressed.…”