Light-Induced Valleytronics in Pristine Graphene
| Autor: | Mrudul, M. S., Jiménez-Galán, Álvaro, Ivanov, Misha, Dixit, Gopal |
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| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | Optica 8, 422-427 (2021) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1364/OPTICA.418152 |
| Popis: | Electrons in two-dimensional hexagonal materials have valley degree of freedom, which can be used to encode and process quantum information. The valley-selective excitations, governed by the circularly polarised light resonant with the material's band-gap, continues to be the foundation of valleytronics. It is often assumed that achieving valley selective excitation in pristine graphene with all-optical means is not possible due to the inversion symmetry of the system. Here we demonstrate that both valley-selective excitation and valley-selective high-harmonic generation can be achieved in pristine graphene by using the combination of two counter-rotating circularly polarized fields, the fundamental and its second harmonic. Controlling the relative phase between the two colours allows us to select the valleys where the electron-hole pairs and higher-order harmonics are generated. We also describe an all-optical method for measuring valley polarization in graphene with a weak probe pulse. This work offers a robust recipe to write and read valley-selective electron excitations in materials with zero bandgap and zero Berry curvature. Comment: 16 pages, 4 figures |
| Databáze: | arXiv |
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