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#### Observation of giant spin-split Fermi-arc with maximal Chern number in the chiral topological semimetal PtGa

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##### Citation

Yao, M., Manna, K., Yang, Q., Fedorov, A., Voroshnin, V., Schwarze, B. V., et al. (2020).
Observation of giant spin-split Fermi-arc with maximal Chern number in the chiral topological semimetal PtGa.*
Nature Communications,* *11*: 2033, pp. 1-7. doi:10.1038/s41467-020-15865-x.

Cite as: https://hdl.handle.net/21.11116/0000-0006-6353-D

##### Abstract

Non-symmorphic chiral topological crystals host exotic multifold fermions, and their associated Fermi arcs helically wrap around and expand throughout the Brillouin zone between the high-symmetry center and surface-corner momenta. However, Fermi-arc splitting and realization of the theoretically proposed maximal Chern number rely heavily on the spin-orbit coupling (SOC) strength. In the present work, we investigate the topological states of a new chiral crystal, PtGa, which has the strongest SOC among all chiral crystals reported to date. With a comprehensive investigation using high-resolution angle-resolved photoemission spectroscopy, quantum-oscillation measurements, and state-of-the-art ab initio calculations, we report a giant SOC-induced splitting of both Fermi arcs and bulk states. Consequently, this study experimentally confirms the realization of a maximal Chern number equal to ±4 in multifold fermionic systems, thereby providing a platform to observe large-quantized photogalvanic currents in optical experiments. © 2020, The Author(s).