Seminarium Fizyki Ciała Stałego

The Coulomb interaction in transition metal dichalcogenide monolayersresults in strongly bound excitons which dominate the optical responseof these materials. Despite a large number of studies, an understandingof how Coulomb and many-body correlation effects affect the excitonicresonances on a femtosecond time scale is still lacking. In order toclarify this question, we consider the excitonic shifts induced by theintense circularly-polarized non-resonant pump pulse applied normally tothe monolayer. We observe experimentally valley-selective (optical Starkand Bloch-Siegert) transient blue shifts of both 1s A and B excitontransitions. We use semiconductor Bloch equations for the theoreticaldescription of the shifts. The solutions of these equations are obtainedwith a modified perturbation technique, which takes into accountmany-body and Coulomb interaction effects. These solutions allow us toexplain the polarization dependence of the observed shifts and calculatetheir values analytically. UwagaSeminarium w trybie HybrydowymFaculty of Physics room 0.06link to remote mode:https://zoom.us/j/7218838148szczegóły patrz instrukcja :instrukcja: (pdf file)AttentionThe seminar in the Hybrid modeFaculty of Physics room 0.06for details see instruction :instruction: (pdf file)