| Autor: |
Ho, Yi Wei, Rosa, Henrique Guimarães, Verzhbitskiy, Ivan, Rodrigues, Manuel Jose de Lima Ferreira, Taniguchi, Takashi, Watanabe, Kenji, Eda, Goki, Pereira, Vitor Manuel, Gomes, José Carlos Viana |
| Rok vydání: |
2019 |
| Předmět: |
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| Druh dokumentu: |
Working Paper |
| DOI: |
10.1021/acsphotonics.0c00174 |
| Popis: |
A population imbalance at different valleys of an electronic system lowers its effective rotational symmetry. We introduce a technique to measure such imbalance - a valley polarization - that exploits the unique fingerprints of this symmetry reduction in the polarization-dependent second-harmonic generation (SHG). We present the principle and detection scheme in the context of hexagonal two-dimensional crystals, which include graphene-based systems and the family of transition metal dichalcogenides, and provide a direct experimental demonstration using a 2H-MoSe$_{2}$ monolayer at room temperature. We deliberately use the simplest possible setup, where a single pulsed laser beam simultaneously controls the valley imbalance and tracks the SHG process. We further developed a model of the transient population dynamics which analytically describes the valley-induced SHG rotation in very good agreement with the experiment. In addition to providing the first experimental demonstration of the effect, this work establishes a conceptually simple, com-pact and transferable way of measuring instantaneous valley polarization, with direct applicability in the nascent field of valleytronics. |
| Databáze: |
arXiv |
| Externí odkaz: |
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