Candidates for the origin of many-body spectral features in monolayer WSe2.

The combination of strong Coulomb interaction, spin and valley degrees of freedom give rise to multiple optical peaks in the spectrum of WSe2. While the physics of many peaks has been identified, the origin of a strong low-energy peak in highly electron-doped WSe2 remains elusive since its first observation in 2013 [1]. In this talk, we show possible explanations for the origin of this optical transition including the interaction of excitons with intervalley plasmons [2,3,4], or magnons induced by resident electrons. We explain why the proposed mechanisms are suitable for the peak to emerge in the spectrum of electron-doped WSe2 while being absent in hole-doped regime or in the whole spectrum of MoSe2 monolayer [5].

[1] A. M. Jones et. al., Nat. Nanotechnol. 8, 634 (2013).
[2] Hanan Dery, Phys. Rev. B 94, 075421 (2016).
[3] Dinh Van Tuan et. al., arXiv:1901.02567.
[4] Dinh Van Tuan et. al., Phys. Rev. X 7, 041040 (2017)
[5] Benedikt Scharf et. al., Journal of Physics: Condensed Matter 31(20), 23001 (2019)