{"id":63908,"date":"2020-09-10T16:41:00","date_gmt":"2020-09-10T13:41:00","guid":{"rendered":"https:\/\/en.buradabiliyorum.com\/spectral-classification-of-excitons\/"},"modified":"2020-09-10T16:41:00","modified_gmt":"2020-09-10T13:41:00","slug":"spectral-classification-of-excitons","status":"publish","type":"post","link":"https:\/\/buradabiliyorum.com\/en\/spectral-classification-of-excitons\/","title":{"rendered":"#Spectral classification of excitons"},"content":{"rendered":"

“#Spectral classification of excitons<\/strong>”<\/p>\n

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\"Spectral<\/img>
\n Credit: Ludwig Maximilian University of Munich
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Ultrathin layers of tungsten diselenide have potential app<\/a>lications in opto-electronics and quantum technologies. LMU researchers have now explored how this material interacts with light in the presence of strong magnetic fields.<\/p>\n

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Owing to their astonishing and versatile properties, atomically thin monolayer and bilayer forms of semiconducting transition metal dichalcogenides have aroused great interest in recent years. Most attention has so far been paid to the optical properties of these materials, such as molybdenum sulfide (MoS) and tungsten diselenide (WSe2<\/sub>). These compounds show great promise as nanoscale elements for applications in opto-electronic and quantum technologies. <\/p>\n

In a new study, LMU physicists led by Alexander H\u00f6gele have now developed a theoretical model, which describes the effects of magnetic fields on the behavior of excitons in two-dimensional ultrathin transition metal dichalcogenides. Excitons are strongly bound quasiparticles, composed of an electron in the conduction band and its positively charged counterpart in the valence band referred to as a hole. In the presence of strong magnetic fields, the energy states of such quasiparticles (i.e. the frequencies at which they emit and absorb light) split up. This spectral splitting can be experimentally measured and\u2014more importantly in the present context\u2014it can also be theoretically predicted.
\nIn the study, the team cooled monolayer and bilayer samples of WSe2<\/sub> to the temperature of liquid helium of a few degrees Kelvin. The researchers then used optical spectroscopy to measure the emission spectra as a function of magnetic field up to 9 Tesla and determined the field-induced splitting. “Measurements like this are useful to study excitons, which in turn determine the light-matter interaction of semiconductors,” H\u00f6gele explains.
\nIt was already known that excitons can form in different configurations. In addition to bright excitons, which couple directly to light, the pairing of electrons and holes can produce spin-dark and momentum-dark excitons. Up to now, it has not been possible to conclusively assign the signatures observed in emission spectra to these different exciton species. In the presence of magnetic field, however, individual emission peaks exhibit characteristic spectral splittings. “This splitting can be used to discriminate between the various types of excitons,” says H\u00f6gele, “but only if we have the according theoretical model.” The LMU team developed theory to calculate from first principles the spectral splitting for the different types of excitons in monolayer and bilayer WSe2<\/sub> subjected to magnetic field, and compared their theoretical predictions with the experimental data.
\nThe results provide a better understanding of the opto-electronic properties of WSe2<\/sub> and related transition-metal dichalcogenides where excitons represent the primary interface for light to interact with nanoscale matter. Ultrathin layers of WSe2<\/sub> serve as a testbed for technological exploitations of light-matter coupling in opto-electronic devices including photodetectors and emitters or photovoltaic devices. “These ultrathin materials are mechanically flexible and extremely compact,” says H\u00f6gele. They are also potentially viable for quantum technologies as they host valleys as quantum degrees of freedom that can serve as qubits, the basic units of information processing in quantum computers.<\/p>\n

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More information:<\/strong>
\n Jonathan F\u00f6rste et al. Exciton g-factors in monolayer and bilayer WSe2<\/sub> from experiment and theory, Nature Communications<\/i> (2020). DOI: 10.1038\/s41467-020-18019-1\n <\/div>\n

\n Citation<\/strong>:
\n Spectral classification of excitons (2020, September 10)
\n retrieved 10 September 2020
\n from https:\/\/phys.org\/news<\/a>\/2020-09-spectral-classification-excitons.html<\/p>\n

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“#Spectral classification of excitons” Credit: Ludwig Maximilian University of Munich Ultrathin layers of tungsten diselenide have potential applications in opto-electronics and quantum technologies. LMU researchers have now explored how this material interacts with light in the presence of strong magnetic fields. Owing to their astonishing and versatile properties, atomically thin monolayer and bilayer forms of…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"fifu_image_url":"","fifu_image_alt":"","footnotes":""},"categories":[16],"tags":[10608,67093],"class_list":["post-63908","post","type-post","status-publish","format-standard","hentry","category-sciencee","tag-quantum-physics","tag-spectral-classification-of-excitons"],"_links":{"self":[{"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/posts\/63908","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/comments?post=63908"}],"version-history":[{"count":0,"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/posts\/63908\/revisions"}],"wp:attachment":[{"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/media?parent=63908"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/categories?post=63908"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/tags?post=63908"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}