Spin dependent bandgap renormalization and state filling effect in Bi$_2$Se$_3$ observed by ultrafast Kerr rotation
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arXiv
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| Autori principali: | , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2024
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| _version_ | 1866910454588112896 |
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| author | Kikuchi, Kazuhiro Mizukoshi, Yu Fukuda, Takumi Fons, Paul Hase, Muneaki |
| author_facet | Kikuchi, Kazuhiro Mizukoshi, Yu Fukuda, Takumi Fons, Paul Hase, Muneaki |
| contents | We investigate the ultrafast spin dynamics of the prototypical topological insulator $\mathrm{Bi_{2}Se_{3}}$ using time-resolved Kerr-rotation (polarization-change) measurements across near-infrared wavelengths. The Kerr-rotation angle $Δθ_{K}$ of $\mathrm{Bi_{2}Se_{3}}$ was found to significantly depend on photon energy around a resonance transition ($\sim 1.0\ \mathrm{eV}$) of bulk states, as well as the ellipticity of the pump light, in the presence of spin excitation. The observed photon-energy dependence of $Δθ_{K}$ can be well simulated by assuming spin-dependent refractive-index changes in the presence of band-gap renormalization and state-filling effect upon photoexcitation. Our study delivers comprehensive insights into the opto-spintronic properties of bulk $\mathrm{Bi_{2}Se_{3}}$ and the fundamental physical processes underlying polarization changes. These findings are expected to be crucial in developing ultrafast magneto-optical memory devices, which can perform read-and-write operations in the Terahertz regime. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2405_12869 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Spin dependent bandgap renormalization and state filling effect in Bi$_2$Se$_3$ observed by ultrafast Kerr rotation Kikuchi, Kazuhiro Mizukoshi, Yu Fukuda, Takumi Fons, Paul Hase, Muneaki Materials Science We investigate the ultrafast spin dynamics of the prototypical topological insulator $\mathrm{Bi_{2}Se_{3}}$ using time-resolved Kerr-rotation (polarization-change) measurements across near-infrared wavelengths. The Kerr-rotation angle $Δθ_{K}$ of $\mathrm{Bi_{2}Se_{3}}$ was found to significantly depend on photon energy around a resonance transition ($\sim 1.0\ \mathrm{eV}$) of bulk states, as well as the ellipticity of the pump light, in the presence of spin excitation. The observed photon-energy dependence of $Δθ_{K}$ can be well simulated by assuming spin-dependent refractive-index changes in the presence of band-gap renormalization and state-filling effect upon photoexcitation. Our study delivers comprehensive insights into the opto-spintronic properties of bulk $\mathrm{Bi_{2}Se_{3}}$ and the fundamental physical processes underlying polarization changes. These findings are expected to be crucial in developing ultrafast magneto-optical memory devices, which can perform read-and-write operations in the Terahertz regime. |
| title | Spin dependent bandgap renormalization and state filling effect in Bi$_2$Se$_3$ observed by ultrafast Kerr rotation |
| topic | Materials Science |
| url | https://arxiv.org/abs/2405.12869 |