Host–Guest Superstructures on Graphene-Based Kagome Lattice

The Kagome lattice of iron phthalocyanine (FePc) on the graphene moiré pattern is employed as host template for two kinds of guest molecules, FePc and <i>tert</i>-butyl zinc phthalocyanine ((<i>t</i>-Bu)₄–ZnPc), to fabricate stable host–guest molecular superstructures. Both FePc and (<i>t</i>-Bu)₄–ZnPc molecules prefer to occupy the nanoscale pores of the Kagome lattice. Ordered superstructures with alternate rows of FePc and (<i>t</i>-Bu)₄–ZnPc are formed after coadsorption of these two species with a ratio of 1:1 on the Kagome lattice. We elucidate that formation of ordered superstructures of guest FePc and (<i>t</i>-Bu)₄–ZnPc are controlled by long-range interaction between the guest molecules mediated by the host Kagome lattice with additional contribution from the graphene/Ru(0001) substrate

Effective Manipulation of a Colossal Second-Order Transverse Response in an Electric-Field-Tunable Graphene Moiré System

The second-order nonlinear transport illuminates a frequency-doubling response emerging in quantum materials with a broken inversion symmetry. The two principal driving mechanisms, the Berry curvature dipole and the skew scattering, reflect various information including ground-state symmetries, band dispersions, and topology of electronic wave functions. However, effective manipulation of them in a single system has been lacking, hindering the pursuit of strong responses. Here, we report on the effective manipulation of the two mechanisms in a single graphene moiré superlattice, AB-BA stacked twisted double bilayer graphene. Most saliently, by virtue of the high tunability of moiré band structures and scattering rates, a record-high second-order transverse conductivity ∼ 510 μm S V–1 is observed, which is orders of magnitude higher than any reported values in the literature. Our findings establish the potential of electrically tunable graphene moiré systems for nonlinear transport manipulations and applications