Doping Tuned the Carrier Dynamics in Li-Doped Bi<sub>2</sub>Se<sub>3</sub> Crystals Revealed by Femtosecond Transient Optical Spectroscopy
Topological insulators (TIs) can be widely applied in the fields of ultrafast optical and spintronic devices owing to the existence of topologically protected gapless Dirac surface states. However, the study of ultrafast dynamics of carriers in TIs remains elusive. In this work, the carrier dynamics...
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MDPI AG
2025-06-01
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| author | Qiya Liu Min Zhang Xinsheng Yang Tixian Zeng Minghu Pan |
| author_facet | Qiya Liu Min Zhang Xinsheng Yang Tixian Zeng Minghu Pan |
| author_sort | Qiya Liu |
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| description | Topological insulators (TIs) can be widely applied in the fields of ultrafast optical and spintronic devices owing to the existence of topologically protected gapless Dirac surface states. However, the study of ultrafast dynamics of carriers in TIs remains elusive. In this work, the carrier dynamics of Li-doped Bi<sub>2−x</sub>Se<sub>3</sub> single crystals were investigated by femtosecond (fs) transient optical spectroscopy (ΔR/R(t) signals). The temperature dependence for the relaxation rates of the electron–electron interaction and electron–phonon coupling is consistent with the results of electrical transport, which indicates the carrier dynamics of TI is highly related with carrier concentrations. We find that the carrier type and concentration of Bi<sub>2</sub>Se<sub>3</sub> can be tuned by Li doping, leading to a metal-insulation transition at low temperatures (T ≤ 55 K), indicating that electron–electron interactions are dominant at low temperature. For T > 55 K, electron–phonon coupling in the bulk carriers becomes the main electric transport mechanism. |
| format | Article |
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| institution | Matheson Library |
| issn | 2079-4991 |
| language | English |
| publishDate | 2025-06-01 |
| publisher | MDPI AG |
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| series | Nanomaterials |
| spelling | doaj-art-77f7be9fc02d4f4fb8cbaf3ad5d421e72025-07-11T14:41:29ZengMDPI AGNanomaterials2079-49912025-06-011513101010.3390/nano15131010Doping Tuned the Carrier Dynamics in Li-Doped Bi<sub>2</sub>Se<sub>3</sub> Crystals Revealed by Femtosecond Transient Optical SpectroscopyQiya Liu0Min Zhang1Xinsheng Yang2Tixian Zeng3Minghu Pan4College of Optoelectronic Technology, Chengdu University of Information Technology, Chengdu 610225, ChinaSchool of Physics and Astronomy, China West Normal University, Nanchong 637002, ChinaSuperconductivity and New Energy R&D Center, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, ChinaCollege of Optoelectronic Technology, Chengdu University of Information Technology, Chengdu 610225, ChinaSchool of Physics and Information, Shanxi Normal University, Xi’an 710119, ChinaTopological insulators (TIs) can be widely applied in the fields of ultrafast optical and spintronic devices owing to the existence of topologically protected gapless Dirac surface states. However, the study of ultrafast dynamics of carriers in TIs remains elusive. In this work, the carrier dynamics of Li-doped Bi<sub>2−x</sub>Se<sub>3</sub> single crystals were investigated by femtosecond (fs) transient optical spectroscopy (ΔR/R(t) signals). The temperature dependence for the relaxation rates of the electron–electron interaction and electron–phonon coupling is consistent with the results of electrical transport, which indicates the carrier dynamics of TI is highly related with carrier concentrations. We find that the carrier type and concentration of Bi<sub>2</sub>Se<sub>3</sub> can be tuned by Li doping, leading to a metal-insulation transition at low temperatures (T ≤ 55 K), indicating that electron–electron interactions are dominant at low temperature. For T > 55 K, electron–phonon coupling in the bulk carriers becomes the main electric transport mechanism.https://www.mdpi.com/2079-4991/15/13/1010topological insulatorsfemtosecond transient optical spectroscopycarrier dynamics |
| spellingShingle | Qiya Liu Min Zhang Xinsheng Yang Tixian Zeng Minghu Pan Doping Tuned the Carrier Dynamics in Li-Doped Bi<sub>2</sub>Se<sub>3</sub> Crystals Revealed by Femtosecond Transient Optical Spectroscopy Nanomaterials topological insulators femtosecond transient optical spectroscopy carrier dynamics |
| title | Doping Tuned the Carrier Dynamics in Li-Doped Bi<sub>2</sub>Se<sub>3</sub> Crystals Revealed by Femtosecond Transient Optical Spectroscopy |
| title_full | Doping Tuned the Carrier Dynamics in Li-Doped Bi<sub>2</sub>Se<sub>3</sub> Crystals Revealed by Femtosecond Transient Optical Spectroscopy |
| title_fullStr | Doping Tuned the Carrier Dynamics in Li-Doped Bi<sub>2</sub>Se<sub>3</sub> Crystals Revealed by Femtosecond Transient Optical Spectroscopy |
| title_full_unstemmed | Doping Tuned the Carrier Dynamics in Li-Doped Bi<sub>2</sub>Se<sub>3</sub> Crystals Revealed by Femtosecond Transient Optical Spectroscopy |
| title_short | Doping Tuned the Carrier Dynamics in Li-Doped Bi<sub>2</sub>Se<sub>3</sub> Crystals Revealed by Femtosecond Transient Optical Spectroscopy |
| title_sort | doping tuned the carrier dynamics in li doped bi sub 2 sub se sub 3 sub crystals revealed by femtosecond transient optical spectroscopy |
| topic | topological insulators femtosecond transient optical spectroscopy carrier dynamics |
| url | https://www.mdpi.com/2079-4991/15/13/1010 |
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