Electronic structure of twisted multilayer graphene
일 시 : 2021년 09월 09일 목요일 16:00
연 사 : 정 재 일 교수 (서울시립대학교 물리학과)
장 소 : 온라인 진행 ( https://us02web.zoom.us/j/81101834598?pwd=RkZIdXJLL1lOWXBjamc2Ylg3VUtRZz09 )
HOST : 신 상 진 교수님
초 록
Twisted bilayer graphene is the paradigmatic example of a moire material where the quasiparticle velocity can be progressively reduced by decreasing the twist angle between the graphene layers, whose bandwidth becomes nearly flat at the so called magic angle near ~1o. At the heart of this spectacular electronic structure modification rests the moire superlattice structure of the interlayer tunneling profile whose period is orders of magnitude larger than the underlying crystal’s lattice constant. In this presentation I will discuss how the moire bands theory allows to obtain the electronic structure of incommensurable crystal systems and how these can be applied for different types of graphene based moire materials. Our studies indicate that the conditions for band narrowing and isolation can be expected in a variety of twisted graphene systems and are achieved more easily when the constituent materials have a band gap, which in rhombohedrally stacked multilayers can be produced by a perpendicular electric field.