Nicolas A Morales Duran, Department of Physics, UT Austin

"Correlated phases of semiconductor moiré materials at fractional fillings"

Abstract: I will discuss recent progress in understanding the correlated phases in flat bands of semiconductor moiré materials, focusing on fractional fillings of both topologically trivial and non-trivial bands. For topologically trivial bands in TMD heterobilayers, we analyze the generalized Wigner crystal states. We show that the crystals have tunable magnetic properties, which we explain using a low-energy effective spin model description. We also investigate the Mott-Wigner transitions at different fillings, finding that they are not strongly first order. For a C=1 Chern band in TMD homobilayers, we compute the quantum geometric tensor and show that for a range of experimentally relevant parameters the band is close to satisfying the ideal condition, indicating that fractional Chern insulators could be stabilized. We confirm this by an exact diagonalization analysis of the system as a function of twist angle and applied pressure.