Description |
Over the last 15 years there have been exciting developments in condensed matter physics and topological properties have been experimentally probed. A revolution was possible because of engineering of novel effective Hamiltonians. The electronic bands in such materials possess Berry curvature and topological invariants like Chern numbers due to quantum properties of the wavefunctions. While Berry curvature [1] and its effects in materials have been studied, detecting changes in the topological invariant, Chern number, is challenging. We show in our experiments, using moiré bilayer graphene, that the first moment of Berry curvature detects topological transitions in the electronic bands. In our experiment, the perpendicular electric field tunes the valley Chern number and the Berry curvature dipole simultaneously permitting us to probe the physics of topological transitions [2].
References:
[1] Sinha* and Adak* et al. Nature Communications, 11, 5548 (2020).
[2] Sinha* and Adak* et al. arXiv:2204.02848, accepted at Nature Physics .
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