Flipping exciton angular momentum with chiral phonons in MoSe$_2$/WSe$_2$ heterobilayers
| Autor: | Delhomme, A., Vaclavkova, D., Slobodeniuk, A., Orlita, M., Potemski, M., Basko, D. M., Watanabe, K., Taniguchi, T., Mauro, D., Barreteau, C., Giannini, E., Morpurgo, A. F., Ubrig, N., Faugeras, C. |
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| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | 2D Materials 7 041002 (2020) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1088/2053-1583/aba567 |
| Popis: | Identifying quantum numbers to label elementary excitations is essential for the correct description of light-matter interaction in solids. In monolayer semiconducting transition metal dichalcogenides (TMDs) such as MoSe$_2$ or WSe$_2$, most optoelectronic phenomena are described well by labelling electron and hole states with the spin projection along the normal to the layer (S$_z$). In contrast, for WSe$_2$/MoSe$_2$ interfaces recent experiments show that taking S$_z$ as quantum number is not a good approximation, and spin mixing needs to be always considered. Here we argue that the correct quantum number for these systems is not S$_z$, but the $z$-component of the total angular momentum -- J$_z$ = L$_z$ + S$_z$ -- associated to the C$_3$ rotational lattice symmetry, which assumes half-integer values corresponding modulo 3 to distinct states. We validate this conclusion experimentally through the observation of strong intervalley scattering mediated by chiral optical phonons that -- despite carrying angular momentum 1 -- cause resonant intervalley transitions of excitons, with an angular momentum difference of 2. Comment: are welcome |
| Databáze: | arXiv |
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