{"date_created":"2018-12-11T11:46:13Z","abstract":[{"text":"The valley pseudospin in monolayer transition metal dichalcogenides (TMDs) has been proposed as a new way to manipulate information in various optoelectronic devices. This relies on a large valley polarization that remains stable over long time scales (hundreds of nanoseconds). However, time-resolved measurements report valley lifetimes of only a few picoseconds. This has been attributed to mechanisms such as phonon-mediated intervalley scattering and a precession of the valley pseudospin through electron-hole exchange. Here we use transient spin grating to directly measure the valley depolarization lifetime in monolayer MoSe2. We find a fast valley decay rate that scales linearly with the excitation density at different temperatures. This establishes the presence of strong exciton-exciton Coulomb exchange interactions enhancing the valley depolarization. Our work highlights the microscopic processes inhibiting the efficient use of the exciton valley pseudospin in monolayer TMDs. ","lang":"eng"}],"status":"public","date_updated":"2021-01-12T07:53:20Z","publication":"Nano Letters","intvolume":"        18","date_published":"2018-01-10T00:00:00Z","quality_controlled":"1","day":"10","year":"2018","author":[{"full_name":"Mahmood, Fahad","first_name":"Fahad","last_name":"Mahmood"},{"id":"45E67A2A-F248-11E8-B48F-1D18A9856A87","last_name":"Alpichshev","full_name":"Alpichshev, Zhanybek","first_name":"Zhanybek","orcid":"0000-0002-7183-5203"},{"full_name":"Lee, Yi","first_name":"Yi","last_name":"Lee"},{"full_name":"Kong, Jing","first_name":"Jing","last_name":"Kong"},{"last_name":"Gedik","full_name":"Gedik, Nuh","first_name":"Nuh"}],"extern":"1","publist_id":"7435","language":[{"iso":"eng"}],"page":"223 - 228","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","main_file_link":[{"open_access":"1","url":"https://arxiv.org/abs/1712.07925"}],"oa":1,"publisher":"American Chemical Society","publication_status":"published","volume":18,"title":"Observation of exciton-exciton interaction mediated valley Depolarization in Monolayer MoSe2","month":"01","issue":"1","external_id":{"arxiv":["1712.07925"]},"doi":"10.1021/acs.nanolett.7b03953","_id":"394","citation":{"apa":"Mahmood, F., Alpichshev, Z., Lee, Y., Kong, J., &#38; Gedik, N. (2018). Observation of exciton-exciton interaction mediated valley Depolarization in Monolayer MoSe2. <i>Nano Letters</i>. American Chemical Society. <a href=\"https://doi.org/10.1021/acs.nanolett.7b03953\">https://doi.org/10.1021/acs.nanolett.7b03953</a>","short":"F. Mahmood, Z. Alpichshev, Y. Lee, J. Kong, N. Gedik, Nano Letters 18 (2018) 223–228.","ieee":"F. Mahmood, Z. Alpichshev, Y. Lee, J. Kong, and N. Gedik, “Observation of exciton-exciton interaction mediated valley Depolarization in Monolayer MoSe2,” <i>Nano Letters</i>, vol. 18, no. 1. American Chemical Society, pp. 223–228, 2018.","mla":"Mahmood, Fahad, et al. “Observation of Exciton-Exciton Interaction Mediated Valley Depolarization in Monolayer MoSe2.” <i>Nano Letters</i>, vol. 18, no. 1, American Chemical Society, 2018, pp. 223–28, doi:<a href=\"https://doi.org/10.1021/acs.nanolett.7b03953\">10.1021/acs.nanolett.7b03953</a>.","chicago":"Mahmood, Fahad, Zhanybek Alpichshev, Yi Lee, Jing Kong, and Nuh Gedik. “Observation of Exciton-Exciton Interaction Mediated Valley Depolarization in Monolayer MoSe2.” <i>Nano Letters</i>. American Chemical Society, 2018. <a href=\"https://doi.org/10.1021/acs.nanolett.7b03953\">https://doi.org/10.1021/acs.nanolett.7b03953</a>.","ama":"Mahmood F, Alpichshev Z, Lee Y, Kong J, Gedik N. Observation of exciton-exciton interaction mediated valley Depolarization in Monolayer MoSe2. <i>Nano Letters</i>. 2018;18(1):223-228. doi:<a href=\"https://doi.org/10.1021/acs.nanolett.7b03953\">10.1021/acs.nanolett.7b03953</a>","ista":"Mahmood F, Alpichshev Z, Lee Y, Kong J, Gedik N. 2018. Observation of exciton-exciton interaction mediated valley Depolarization in Monolayer MoSe2. Nano Letters. 18(1), 223–228."},"type":"journal_article","oa_version":"Submitted Version"}