2026-09-20T01:37:52Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/1202792022-01-13T07:54:07Zcom_1721.1_7582com_1721.1_7581col_1721.1_131024
Pablo D. Jarillo-Herrero.
Mier Valdivia, Andrés M
Massachusetts Institute of Technology. Department of Physics.
Massachusetts Institute of Technology. Department of Physics
2019-02-08T14:19:40Z
2019-02-08T14:19:40Z
2018
2018
http://hdl.handle.net/1721.1/120279
1082865343
Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2018.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 69-72).
In this work, we studied the chiral charge density wave (CDW) phase in titanium diselenide (TiSe₂) with the circular photogalvanic effect (CPGE). Mechanically exfoliated bulk TiSe₂ flakes were obtained and implemented into nanoscale devices using standard fabrication techniques. Four samples' photocurrent response to a 120 meV laser was subsequently measured as a function of temperature and laser power. The onset of the CPGE at approximately 174 K confirms the emergence of chiral order below the regular CDW transition at 197 K. Furthermore, we were able to train the chirality of the system by cooling it while shining circularly polarized light. With this study, we have confirmed that TiSe₂ is a novel kind of material that spontaneously breaks inversion, all mirror, and roto-inversion symmetries and attains gyrotropic order, paving the way for future experimental work on similar condensed matter systems.
by Andrés M. Mier Valdivia.
S.B.
72 pages
eng
Massachusetts Institute of Technology
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
Physics.
Spontaneous chiral ordering in titanium diselenide
Spontaneous chiral ordering in TiSe₂
Thesis
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<Abstract>In this work, we studied the chiral charge density wave (CDW) phase in titanium diselenide (TiSe₂) with the circular photogalvanic effect (CPGE). Mechanically exfoliated bulk TiSe₂ flakes were obtained and implemented into nanoscale devices using standard fabrication techniques. Four samples' photocurrent response to a 120 meV laser was subsequently measured as a function of temperature and laser power. The onset of the CPGE at approximately 174 K confirms the emergence of chiral order below the regular CDW transition at 197 K. Furthermore, we were able to train the chirality of the system by cooling it while shining circularly polarized light. With this study, we have confirmed that TiSe₂ is a novel kind of material that spontaneously breaks inversion, all mirror, and roto-inversion symmetries and attains gyrotropic order, paving the way for future experimental work on similar condensed matter systems.</Abstract>
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