The electronic properties of materials are determined by the atomic constituents and their crystal lattice structure. Engineered electronic materials, which are created by applying a designed spatially periodic potential, a superlattice, have offered a powerful way to alter the properties of natural crystals in a controlled manner. For example, Moire superlattices, where different layers of two-dimensional (2D) materials are stacked and twisted to create a superlattice modulation potential, are currently attracting significant attention as they provide a ideal platform for both studying fundamental physics as well as promising future applications.
Imposing spatially periodic electric field via patterned dielectric material or metallic gate has also been proven to be a powerful technique to create a superlattice. It offers an excellent control of the lattice parameters and can be easily integrated into many existing device architectures, e.g. a semiconductor FET, which has an advantage of well-established fabrication technology and superb device quality.
Using this approach, we demonstrate formation of artificial Fermi surfaces by applying a weak modulation potential and measuring quantum oscillations in the magnetoresistance. Furthermore, we increase the potential modulation to create an artificial 2D bandstructure. The low field Hall resistance shows multiple transitions from electron-like to hole-like behaviour as the chemical potential is swept through the different artificial bands, consistent with our band structure calculations. We are able to continuously tune the artificial bandstructure from free electrons to those of electrons in graphene-like and eventually Kagome-like bands.
Virtual session will be streamed, here: https://uwa.zoom.us/j/83937347857?pwd=Ym1WSXBFSVV6SWt2TERyQ040ZElaQT09