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주관: 기초과학연구소(자율운영 중점연구소지원사업)

일시: 2023년 11월 29일 수요일 17:00

장소: 원천관 502호

연사: 임준원 교수(아주대학교 물리학과)

주제: Topology and symmetry of Bloch states from the point of view of compact localized states

A compact localized state (CLS) is a characteristic localized eigenstate of a flat band [1,2]. A CLS has nonzero amplitudes only inside a finite spatial region while precisely zero outside due to the quantum destructive interference a specific lattice structure provides. While the CLS explains the origin of completely flat bands, which are dispersionless over the whole Brillouin zone, the localization mechanism for partially flat bands ubiquitous in surfaces of topological semimetals has been unknown.

We show that a partially flat band is characterized by a non-normalizable CLS featuring a quasilocalization nature. In this band, one can have the Wannier obstruction even if the band is topologically trivial. We also discuss a novel type of band-crossing protected by symmetry properties of the compact localized states.