Magnetic injection photocurrents in valley polarized states of twisted bilayer graphene
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866915758200586240 |
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| author | Peñaranda, Fernando Ochoa, Héctor de Juan, Fernando |
| author_facet | Peñaranda, Fernando Ochoa, Héctor de Juan, Fernando |
| contents | Magic-angle twisted bilayer graphene displays a complex phase diagram as a function of flat band filling, featuring compressibility cascade transitions and a variety of competing ground states with broken spin, valley and point group symmetries. Recent THz photocurrent spectroscopy experiments have shown a dependence on the filling which is not consistent with the simplest cascade picture of sequential filling of equivalent flat bands. In this work, we show that when time-reversal symmetry is broken due to valley polarization, a magnetic injection photocurrent develops which can be used to distinguish different spin-valley polarization scenarios. Using the topological heavy fermion model we compute both shift and injection currents as a function of filling and argue that current experiments can be used to determine the spontaneous valley polarization. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2501_09703 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Magnetic injection photocurrents in valley polarized states of twisted bilayer graphene Peñaranda, Fernando Ochoa, Héctor de Juan, Fernando Mesoscale and Nanoscale Physics Magic-angle twisted bilayer graphene displays a complex phase diagram as a function of flat band filling, featuring compressibility cascade transitions and a variety of competing ground states with broken spin, valley and point group symmetries. Recent THz photocurrent spectroscopy experiments have shown a dependence on the filling which is not consistent with the simplest cascade picture of sequential filling of equivalent flat bands. In this work, we show that when time-reversal symmetry is broken due to valley polarization, a magnetic injection photocurrent develops which can be used to distinguish different spin-valley polarization scenarios. Using the topological heavy fermion model we compute both shift and injection currents as a function of filling and argue that current experiments can be used to determine the spontaneous valley polarization. |
| title | Magnetic injection photocurrents in valley polarized states of twisted bilayer graphene |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2501.09703 |