Probing Excitonic Correlations and Multipole Screening in Monolayer MoS2 by Photoemission
Woojoo Lee
Department of Physics
Gachon University
Abstract:
Reduced dimensionality and environment-dependent dielectric screening make monolayer MoS2 an ideal platform for studying Coulomb interactions. In this talk, I will present two complementary photoemission studies: time-resolved ARPES measurements that track the ultrafast evolution of a photoexcited electron–hole plasma into correlated excitonic states across a Mott crossover, and temperature-dependent ARPES measurements that reveal a strongly momentum-dependent valence-band renormalization induced by a crossover from monopole-like to multipole-like screening at the MoS₂–graphite interface. Together, these studies show how photoemission spectroscopy can probe both nonequilibrium excitonic correlations and environment-induced quasiparticle band renormalization in a two-dimensional semiconductor.
Bio:
Woojoo Lee received his Ph.D. degree in physics from the University of Texas at Austin in 2021 and later he moved to the University of Chicago for his postdoc position. Currently He is an assistant professor at Gachon University. He utilizes advanced experimental techniques like ultrafast photoemission spectroscopy, molecular beam epitaxy and 2D materials fabrication methods to explore and manipulate novel quantum materials in a desired way.
