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| Main Authors: | , , , , |
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| Format: | Preprint |
| Published: |
2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2603.05816 |
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Table of Contents:
- Recent quantum oscillation experiments on the kagome metals CsTi$_3$Bi$_5$ and RbTi$_3$Bi$_5$ have revealed a puzzling phenomenon: despite possessing nearly identical band structures and Fermi surface geometries, they exhibit distinct oscillation spectra and topological signals. Intuitively, the fundamental distinction between the two compounds originates from the alkali metal ions, where Cs possesses more diffuse orbitals than Rb. By using a tight-binding model, we map this orbital variation into an effective next-nearest-neighbor hopping term. Based on this framework, we successfully reproduce the distinct experimental features. Furthermore, we demonstrate that the physical origin of their distinct topological signals stems from the magnetic breakdown effect. In the RbTi$_3$Bi$_5$ case, magnetic breakdown readily occurs and masks the intrinsic topological nature. In contrast, the presence of the next-nearest-neighbor hopping in CsTi$_3$Bi$_5$ enlarges the hybridization gap, significantly reducing the magnetic breakdown probability and manifesting the nontrivial Berry phase. These findings demonstrate that magnetic breakdown plays an important role in the observation of topological properties and suggest that subtle orbital differences can lead to significant variations in quantum oscillations.