+++ONLINE KOLLOQUIUM+++ (MCQST-Kolloquium) Strong electronic correlations in 2D semiconductors (Prof. Dr. Atac Imamoglu)

  • Datum: 10.11.2020
  • Uhrzeit: 14:30
  • Vortragende(r): Prof. Dr. Atac Imamoglu
  • ETH Zürich, Switzerland
When the Coulomb repulsion between electrons dominates over their kinetic energy, electrons in two dimensional systems were predicted to spontaneously break continuous translation symmetry and form a quantum crystal. Efforts to observe this elusive state of matter, termed a Wigner crystal, in two dimensional extended systems have primarily focused on electrons confined to a single Landau level at high magnetic fields, but have not provided a conclusive experimental signature of the emerging charge order.

In this talk, I will present experiments where we use optical spectroscopy to demonstrate that electrons in a pristine monolayer semiconductor form a Wigner crystal. The interactions between resonantly injected excitons and electrons arranged in a periodic lattice modify the exciton band structure so that it exhibits a new umklapp resonance, heralding the presence of charge order. Remarkably, the combination of a relatively high electron mass and reduced dielectric screening allows us to observe electron crystals even in the absence of external magnetic fields.

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