{"id":9233,"date":"2021-03-10T15:20:00","date_gmt":"2021-03-10T13:20:00","guid":{"rendered":"https:\/\/lncmi.cnrs.fr\/?p=9233"},"modified":"2025-07-07T10:57:08","modified_gmt":"2025-07-07T08:57:08","slug":"dark-excitons-in-metal-dichalcogenide-monolayers","status":"publish","type":"post","link":"https:\/\/lncmi.cnrs.fr\/en\/news\/dark-excitons-in-metal-dichalcogenide-monolayers\/","title":{"rendered":"Dark excitons in metal dichalcogenide monolayers"},"content":{"rendered":"\n<p>Excitons are electronic excitations formed by an electron-hole pair. At low energies (below a few hundreds of meV), they control the optical properties of transition metal dichalcogenide monolayers. Knowledge of the fine structure of these excitons is therefore essential to understand the optoelectronic properties of these 2D materials. Here we have investigated the exciton fine structure of MoS<sub>2<\/sub> and MoSe<sub>2<\/sub> monolayers encapsulated in boron nitride by magneto-photoluminescence spectroscopy in magnetic fields up to 30\u2009T. The experiments performed in transverse magnetic field reveal a brightening of the spin-forbidden dark excitons in MoS<sub>2<\/sub> monolayer: we find that the dark excitons appear at 14\u2009meV below the bright ones (see Figure). Magnetic brightening experiments thus appear crucial to determine the band structure of monolayer semiconductors. These experiments are possible thanks to the high static magnetic fields accessible at LNCMI-G.<\/p>\n\n\n\n<p><strong>Publication<\/strong> &#8211; <strong>Measurement of the Spin-Forbidden Dark Excitons in MoS<sub>2<\/sub> and MoSe<sub>2<\/sub> monolayers<\/strong>Robert, B. Han, P. Kapuscinski, A. Delhomme, C. Faugeras, T. Amand, M. R. Molas, M. Bartos, K. Watanabe, T. Taniguchi, B. Urbaszek, M. Potemski, X. Marie <a href=\"https:\/\/www.nature.com\/articles\/s41467-020-17608-4\">Nature Communications <strong>11<\/strong>, 1037, (2020)<\/a><\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"550\" height=\"516\" src=\"https:\/\/lncmi.cnrs.fr\/wp-content\/uploads\/2021\/03\/D-LEBOEUF.png\" alt=\"\" class=\"wp-image-23171\" srcset=\"https:\/\/lncmi.cnrs.fr\/wp-content\/uploads\/2021\/03\/D-LEBOEUF.png 550w, https:\/\/lncmi.cnrs.fr\/wp-content\/uploads\/2021\/03\/D-LEBOEUF-480x450.png 480w\" sizes=\"(min-width: 0px) and (max-width: 480px) 480px, (min-width: 481px) 550px, 100vw\" \/><\/figure>\n\n\n\n<p><strong>Figure<\/strong> -In-plane magnetic field B<sub>\/\/<\/sub> \u2013 Spin-forbidden dark exciton in MoS<sub>2<\/sub> monolayer encapsulated in hBN revealed by photoluminescence (PL). (a) Color map of the variation of the PL intensity as a function of B<sub>\/\/ <\/sub>&nbsp;(the PL intensity of the bright exciton, X<sub>B<\/sub>, has been normalized at each field); (b) PL spectra for magnetic fields from 0 to 30 T showing the emergence of the brightened dark exciton, X<sub>D<\/sub>, at low energy. (c) Ratio of the PL intensity of dark (X<sub>D<\/sub>) and bright (X<sub>B<\/sub>) excitons as a function of magnetic field. Inset: sketch of the excitonic fine structure. The arrows \u2191 and \u2193 represent the main spin contribution of conduction and valence electrons involved in the exciton states.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Excitons are electronic excitations formed by an electron-hole pair. At low energies (below a few hundreds of meV), they control the optical properties of transition metal dichalcogenide monolayers. Knowledge of [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":23171,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[292],"tags":[],"post_folder":[],"class_list":["post-9233","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news"],"jetpack_featured_media_url":"https:\/\/lncmi.cnrs.fr\/wp-content\/uploads\/2021\/03\/D-LEBOEUF.png","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/lncmi.cnrs.fr\/en\/wp-json\/wp\/v2\/posts\/9233","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lncmi.cnrs.fr\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/lncmi.cnrs.fr\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/lncmi.cnrs.fr\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/lncmi.cnrs.fr\/en\/wp-json\/wp\/v2\/comments?post=9233"}],"version-history":[{"count":0,"href":"https:\/\/lncmi.cnrs.fr\/en\/wp-json\/wp\/v2\/posts\/9233\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/lncmi.cnrs.fr\/en\/wp-json\/wp\/v2\/media\/23171"}],"wp:attachment":[{"href":"https:\/\/lncmi.cnrs.fr\/en\/wp-json\/wp\/v2\/media?parent=9233"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/lncmi.cnrs.fr\/en\/wp-json\/wp\/v2\/categories?post=9233"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lncmi.cnrs.fr\/en\/wp-json\/wp\/v2\/tags?post=9233"},{"taxonomy":"post_folder","embeddable":true,"href":"https:\/\/lncmi.cnrs.fr\/en\/wp-json\/wp\/v2\/post_folder?post=9233"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}