Coherent light-matter interactions in monolayer transition-metal dichalcogenides
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2017.
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| Format: | Thesis |
| Language: | eng |
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Massachusetts Institute of Technology
2017
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| Online Access: | http://hdl.handle.net/1721.1/112070 |
| _version_ | 1826190174030135296 |
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| author | Sie, Edbert Jarvis |
| author2 | Nuh Gedik. |
| author_facet | Nuh Gedik. Sie, Edbert Jarvis |
| author_sort | Sie, Edbert Jarvis |
| collection | MIT |
| description | Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2017. |
| first_indexed | 2024-09-23T08:35:54Z |
| format | Thesis |
| id | mit-1721.1/112070 |
| institution | Massachusetts Institute of Technology |
| language | eng |
| last_indexed | 2024-09-23T08:35:54Z |
| publishDate | 2017 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/1120702019-04-09T18:42:06Z Coherent light-matter interactions in monolayer transition-metal dichalcogenides Sie, Edbert Jarvis Nuh Gedik. Massachusetts Institute of Technology. Department of Physics. Massachusetts Institute of Technology. Department of Physics. Physics. Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2017. Cataloged from PDF version of thesis. Includes bibliographical references (pages 155-164). Semiconductors that are thinned down to a few atomic layers can exhibit novel properties beyond those encountered in bulk forms. Transition-metal dichalcogenides (TMDs) such as MoS 2, WS2 and WSe2 are prime examples of such semiconductors. They appear in layered structure that can be reduced to a stable single layer where remarkable electronic properties can emerge. Monolayer TMDs have a pair of electronic valleys which have been proposed as a new way to carry information in next generation devices, called valleytronics. However, these valleys are normally locked in the same energy level, which limits their potential use for applications. This dissertation presents the optical methods to split their energy levels by means of coherent light-matter interactions. Experiments were performed in a pump-probe technique using a transient absorption spectroscopy on MoS2 and WS2, and a newly developed XUV light source for time and angle-resolved photoemission spectroscopy (TR-ARPES) on WSe2 and WTe 2 Hybridizing the electronic valleys with light allows us to optically tune their energy levels in a controllable valley-selective manner. In particular, by using off-resonance circularly polarized light at small detuning, we can tune the energy level of one valley through the optical Stark effect. At larger detuning, we observe a separate contribution from the so-called Bloch-Siegert effect, a delicate phenomenon that has eluded direct observation in solids. The two effects obey opposite selection rules, which enables us to separate the two effects at two different valleys. Monolayer TMDs also possess strong Coulomb interaction that enhances many-body interactions between excitons, both bonding and non-bonding interactions. In the former, bound excitonic quasiparticles such as biexcitons play a unique role in coherent light-matter interactions where they couple the two valleys to induce opposite energy shifts. In the latter, non-bonding interactions between excitons are found to exhibit energy shifts that effectively mimics the Lennard-Jones interactions between atoms. Through these works, we demonstrate new methods to optically tune the energy levels of electronic valleys in monolayer TMDs. by Edbert Jarvis Sie. Ph. D. 2017-10-30T15:30:11Z 2017-10-30T15:30:11Z 2017 2017 Thesis http://hdl.handle.net/1721.1/112070 1006736365 eng MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission. http://dspace.mit.edu/handle/1721.1/7582 164 pages application/pdf Massachusetts Institute of Technology |
| spellingShingle | Physics. Sie, Edbert Jarvis Coherent light-matter interactions in monolayer transition-metal dichalcogenides |
| title | Coherent light-matter interactions in monolayer transition-metal dichalcogenides |
| title_full | Coherent light-matter interactions in monolayer transition-metal dichalcogenides |
| title_fullStr | Coherent light-matter interactions in monolayer transition-metal dichalcogenides |
| title_full_unstemmed | Coherent light-matter interactions in monolayer transition-metal dichalcogenides |
| title_short | Coherent light-matter interactions in monolayer transition-metal dichalcogenides |
| title_sort | coherent light matter interactions in monolayer transition metal dichalcogenides |
| topic | Physics. |
| url | http://hdl.handle.net/1721.1/112070 |
| work_keys_str_mv | AT sieedbertjarvis coherentlightmatterinteractionsinmonolayertransitionmetaldichalcogenides |