Title : Between Order and Disorder: A New Perspective on the Pseudogap
일시 : 2026년 3월 24일 (화), 17시
장소 : 아산이학관 433호
Speaker : 김근수 (연세대)
Abstracts:
Many fascinating quantum phenomena, including high-temperature superconductivity, have been discovered in two-dimensional layered insulators doped with foreign atoms. Although these dopants are often ignored in theoretical models for the sake of simplicity, they are inevitably present in real materials. More importantly, while they may appear to be randomly distributed at first glance, they can develop short-range order, characterized by broad peaks in the structure factor associated with the average dopant spacing. In this talk, I will present our recent angle-resolved photoemission spectroscopy (ARPES) studies of a pseudogap emerging from the short-range order of dopants. Our experimental platform is black phosphorus, a two-dimensional layered insulator whose surface is doped with alkali metals. We show that the dopant-induced short-range order gives rise to a pseudogap and to an anomalously aperiodic (roton-like) band dispersion. Finally, I will briefly discuss broader implications for the pseudogap in high-temperature superconductors and for recent advances in the measurement of quantum geometry.