Topology and Chirality
Chirality — the property of an object not being superimposable on its mirror image — represents one of nature’s most fundamental symmetry breakings1. While molecular chirality is well established in chemistry and biology, recent advances have revealed chirality as a powerful, tunable degree of freedom in solid-state quantum systems. Topology, originally a mathematical concept, has become indispensable for describing condensed matter2,3. At the heart of topological quantum materials lie chiral electronic states in bulk, surface, and edge modes, where spin and momentum are locked either parallel or anti-parallel4,5. These chiral states manifest in Weyl6-8 and multifold fermion systems10,11, exhibiting phenomena such as chiral anomalies12, Berry curvature monopoles, mixed axial-gravitational responses13 and axions14 that mirror predictions from high-energy physics.
My research has established chiral topological semimetals (e.g., PtAl, PdGa11,15-19, RhSi20,21, PtGa,Te22) and non-collinear antiferromagnets (e.g., Mn₃Sn, Mn₃Ge)23-25 as versatile platforms where structural and electronic chirality can be actively controlled. Structural chirality in crystals gives rise to chiral surface states with enantio-selective orbital angular momentum, opening pathways for spin filtering, magnetochiral anisotropy, and chirality-induced spin selectivity (CISS) 21,26,27. In parallel, topological band structures generate emergent axial fields (Berry curvature, orbital angular momentum, chiral phonons) that propagate chirality across electronic, vibrational, and spin subsystems, enabling “chiral information transfer.”
A particularly transformative aspect of this work connects topological chirality with catalysis28. In structurally chiral and spin-chiral materials, Berry flux and spin textures can tune electrocatalytic selectivity. For example, external magnetic fields in Mn₃Ge and Mn₃Sn switch CO₂ reduction from two-electron to eight-electron pathways29, demonstrating field-controllable catalysis. Similarly, chiral semimetals like PdGa and PtGa exhibit intrinsic spin polarization that enhances enantioselective adsorption and reaction rates30. These results introduce spin chirality as an externally tunable reagent, bridging momentum-space anomalies with real-space chemical transformations.
Beyond static crystal structures, we emergent chirality in correlated electron systems, including chiral charge density waves (CDWs) in kagome metals (e.g., CsV₃Sb₅)31,32 and layered dichalcogenides are future directions. These phases break inversion and mirror symmetries, producing gyrotropic order and unconventional transport such as nonlinear Hall effects without net magnetization. Small magnetic fields can reverse the chirality of these responses, revealing novel symmetry-breaking mechanisms relevant to catalysis and spintronics.
Together, this body of work reframes chirality from a geometric descriptor into a dynamic quantum variable central to next-generation materials design. By intertwining structural chirality, topological band theory, spin textures, and catalytic functionality, our research builds conceptual and experimental bridges across condensed matter physics, chemistry, and even cosmology—where chirality may link the asymmetry of matter and antimatter to the homochirality of life1.
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4 Wu, X., Wang, X. & Felser, C. Chirality meets topology: building quantum bridges to catalysis. La Rivista del Nuovo Cimento 48, 241–273 (2025). doi.org/10.1007/s40766-025-00068-1
5 Yan, B. & Felser, C. Topological Materials: Weyl Semimetals. Ann. Rev. Cond. Mat. Phys. 8, 337–354 (2017).
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10 Gooth, J. et al. Electrical and Thermal Transport at the Planckian Bound of Dissipation in the Hydrodynamic Electron Fluid of WP2. Nat. Commun. 9, 4093 (2018). doi.org/10.48550/arXiv.1706.05925
11 Bradlyn, B. et al. Beyond Dirac and Weyl fermions: Unconventional quasiparticles in conventional crystals. Science 353, aaf5037 (2016). doi.org/10.1126/science.aaf5037
12 Niemann, A. C. et al. Chiral magnetoresistance in the Weyl semimetal NbP. Scientific Reports 7, 43394 (2017). doi.org/10.1038/srep43394
13 Gooth, J. et al. Experimental signatures of the mixed axial–gravitational anomaly in the Weyl semimetal NbP. Nature 547, 324–327 (2017). doi.org/10.1038/nature23005
14 Gooth, J. et al. Axionic charge-density wave in the Weyl semimetal (TaSe4)2I. Nature 575, 315–319 (2019). doi.org/10.1038/s41586-019-1630-4
15 Sessi, P. et al. Handedness-dependent quasiparticle interference in the two enantiomers of the topological chiral semimetal PdGa. Nature Communications 11, 3507 (2020). doi.org/10.1038/s41467-020-17261-x
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17 Schröter, N. B. M. et al. Chiral topological semimetal with multifold band crossings and long Fermi arcs. Nature Physics 15, 759–765 (2019). doi.org/10.1038/s41567-019-0511-y
18 Yen, Y. et al. Controllable orbital angular momentum monopoles in chiral topological semimetals. Nat. Phys. 20, 1912–1918 (2024). doi.org/10.1038/s41567-024-02655-1
19 Krieger, J. A. et al. Weyl spin-momentum locking in a chiral topological semimetal. Nat. Commun. 15, 3720 (2024). doi.org/10.1038/s41467-024-47976-0
20 Sanchez, D. S. et al. Tunable topologically driven Fermi arc van Hove singularities. Nat. Phys. (2023). doi.org/10.1038/s41567-022-01892-6
21 Wang, X. et al. Topological semimetals with intrinsic chirality as spin-controlling electrocatalysts for the oxygen evolution reaction. Nature Energy 10, 101–109 (2025). doi.org/10.1038/s41560-024-01674-9
22 Zhang, H. et al. Measurement of phonon angular momentum. Nature Physics (2025). doi.org/10.1038/s41567-025-02952-3
23 Kübler, J. & Felser, C. Non-collinear Antiferromagnets and the Anomalous Hall Effect. Europhys. Lett. 108, 67001 (2014). doi.org/10.48550/arXiv.1410.5985
24 Nayak, A. K. et al. Large anomalous Hall effect driven by non-vanishing Berry curvature in non-collinear antiferromagnet Mn3Ge Sci. Adv. 2, e1501870 (2016). doi.org/10.1126/sciadv.150187
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26 Yang, Q., Li, Y., Felser, C. & Yan, B. Chirality-induced spin selectivity and current-driven spin and orbital polarization in chiral crystals. Newton 1 (2025). doi.org/10.1016/j.newton.2025.100015
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29 Yugang Gao, N. M., Changjiang Yi, Chandra Shekhar, Xiaodong Li, Walter Schnelle, Horst Borrmann, Paul Simon, Edouard Lesne, Fabian Roman Menges, Yang Zhang, Claudia Felser, Xia Wang. (submitted, 2025).
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