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arXiv · 2501.09703

Magnetic injection photocurrents in valley polarized states of twisted bilayer graphene

Fernando Peñaranda·Héctor Ochoa·Fernando de Juan
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Abstract

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.

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Fernando Peñaranda, Héctor Ochoa, Fernando de Juan. 2025-01-16. Magnetic injection photocurrents in valley polarized states of twisted bilayer graphene. https://doi.org/10.1103/1zsf-kh2q

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