Seminarium Fizyki Ciała Stałego

When the Coulomb repulsion between itinerant electrons dominates over their kinetic energy, the electrons in solid state materials start to develop strong correlations. A paradigm state of matter that is expected to emerge in this regime is an electronic Wigner crystal, in which the electrons spontaneously break continuous translation symmetry and arrange themselves into a periodic lattice mimicking that of the real crystals. In this talk, I will review our recent experimental explorations of strongly correlated electronic phases in transition metal dichalcogenides (TMD) and their van der Waals heterostructures. In particular, I will present our novel spectroscopic technique allowing to detect the Wigner crystal in a TMD monolayer through the periodic potential it generates for the excitons [1]. This potential allows the excitons to undergo a Bragg diffraction, which gives rise to a new, Bragg-umklapp transition in the optical excitation spectrum that heralds the presence of a crystalline electronic order. In the second part of the talk, I will also show how the TMD monolayer can be exploited as a quantum proximity sensor to optically probe the formation of fractional quantum Hall states in a nearby graphene layer [2].[1] T. Smoleński, P. E. Dolgirev, C. Kuhlenkamp, A. Popert, Y. Shimazaki, P. Back, X. Lu, M. Kroner, K. Watanabe, T. Taniguchi, I. Esterlis, E. Demler, and A. Imamoğlu, Signatures of Wigner crystal of electrons in a monolayer semiconductor. Nature 595, 53-57 (2021).[2] A. Popert, Y. Shimazaki, M. Kroner, K. Watanabe, T. Taniguchi, A. Imamoğlu, and T. Smoleński, Optical probing of fractional quantum Hall effect in graphene. to be published (2021).UwagaSeminarium w trybie hybrydowympatrz instrukcja :instrukcja: (pdf file)AttentionThe seminar in the hybrid modesee instruction :instruction: (pdf file)