Floquet-Engineered Valley-Topotronics in Kekulé-Y Bond Textured Graphene Superlattice
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arXiv
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| Natura: | Preprint |
| Pubblicazione: |
2024
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| _version_ | 1866917795968581632 |
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| author | Saha, Sushmita Mawrie, Alestin |
| author_facet | Saha, Sushmita Mawrie, Alestin |
| contents | The exquisite distortion in a Kekulé-Y (Kek-Y) superlattice merges the two inequivalent Dirac cones (from the $K$- and the $K^\prime$- points) into the highest symmetric $Γ$-point in the hexagonal Brillouin zone. Here we report that a circularly polarised light not only opens up a topological gap at the $Γ$-point but also lifts the valley degeneracy at that point. Endowed with Floquet dynamics and by devising a scheme of high-frequency approximation, we have proposed that the handedness (left/right) in polarised light offers the possibility to realise the valley-selective circular dichroism in Kek-Y shaped graphene superlattice. Also, the non-vanishing Berry curvature and enumeration of valley resolved Chern number $\mathcal{C}_{K}/\mathcal{C}_{K^\prime}=+1/-1$ enable us to assign two pseudo-spin flavors (up/down) with the two valleys. Thereby, the above observations confirm the topological transition suggesting the ease of realising the valley quantum anomalous Hall (VQAH) state within the photon-dressed Kek-Y. These findings further manifest a non-zero optical valley polarisation which is maximum at the $Γ$-point. Our paper thus proposes an optically switchable topological valley filter which is desirous in the evolving landscape of valleytronics. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2401_09762 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Floquet-Engineered Valley-Topotronics in Kekulé-Y Bond Textured Graphene Superlattice Saha, Sushmita Mawrie, Alestin Mesoscale and Nanoscale Physics The exquisite distortion in a Kekulé-Y (Kek-Y) superlattice merges the two inequivalent Dirac cones (from the $K$- and the $K^\prime$- points) into the highest symmetric $Γ$-point in the hexagonal Brillouin zone. Here we report that a circularly polarised light not only opens up a topological gap at the $Γ$-point but also lifts the valley degeneracy at that point. Endowed with Floquet dynamics and by devising a scheme of high-frequency approximation, we have proposed that the handedness (left/right) in polarised light offers the possibility to realise the valley-selective circular dichroism in Kek-Y shaped graphene superlattice. Also, the non-vanishing Berry curvature and enumeration of valley resolved Chern number $\mathcal{C}_{K}/\mathcal{C}_{K^\prime}=+1/-1$ enable us to assign two pseudo-spin flavors (up/down) with the two valleys. Thereby, the above observations confirm the topological transition suggesting the ease of realising the valley quantum anomalous Hall (VQAH) state within the photon-dressed Kek-Y. These findings further manifest a non-zero optical valley polarisation which is maximum at the $Γ$-point. Our paper thus proposes an optically switchable topological valley filter which is desirous in the evolving landscape of valleytronics. |
| title | Floquet-Engineered Valley-Topotronics in Kekulé-Y Bond Textured Graphene Superlattice |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2401.09762 |