Abstract
Electromagnetic response has become the most powerful way for detecting, controlling and displaying in all kinds of electronics. Though the well-developed band theory based on mean field approximation plays an essential role in understanding and designing semiconductor devices, phenonmena as fractional quantized Hall conductance and high-temperature superconductivity have been challenging its prediction ability. At the same time, with the discovery of a new experimental method (i.e. twisting) tuning band flatness of two dimensional materials represented by twisted bilayer graphene, all kinds of strong correlation phenomena emerged and call researchers from different fields join this party.
In this seminar, following a brief introduction, the speaker will talk about his study within three typical two dimensional flat band systems, i.e., twisted bilayer graphene, twisted transition metal dichalcogenides and Landau level with moiré potential respectively. Flat band limit is usually taken in analytical derivation, and determinant quantum Monte Carlo is the main numerical methodology used at all kinds of integer fillings. Order and degeneracy of ground state, single-particle and two-particle Green’s function and excitation spectra, finite temperature phase and phase transition, linear and nonlinear conductance are main results for the involved topics.
Anyone interested is welcome to attend.