General Physics Colloquium, Dr. Claudia Felser, Max Planck Institute for Chemical Physics of Solids

Title:  Chirality and Topology

Host:  Kin Fai Mak

Abstract:  

Chirality is a very active field of research in organic chemistry, closely linked to the concept of symmetry. Topology, a well-established concept in mathematics, has become essential to describe condensed matter systems [1,2]. At its core are chiral electron states on the bulk, surfaces, and edges of materials, where spin and momentum are locked parallel or anti-parallel. Magnetic and non-magnetic Weyl semimetals exhibit chiral bulk states that realize predictions from high-energy and astrophysics, such as the chiral anomaly, the mixed axial-gravitational anomaly, and axions [3–5].

Chiral topological crystals host robust chiral surface states [6,7] and exhibit enantio-selective orbital angular momentum, advantageous in catalysis. Recently, topological quantum materials have emerged as catalysts where Berry flux and magnetic spin textures enable control over reactivity and selectivity. For example, in chiral antiferromagnets such as Mn₃Ge and Mn₃Sn, the Berry curvature can be dynamically tuned by an external magnetic field, switching electrocatalytic CO₂ reduction selectivity from two-electron (CO, HCOOH) to eight-electron (CH₄) products [9].

Extending this concept to enantioselective molecular reactions, we will developed a method for magnetic-field-controlled asymmetric catalysis using topological antiferromagnets, in which the enantioselectivity of chiral molecule reduction  is governed by the magnetization direction of Mn₃Ge or Mn₃Sn. This approach will introduce the spin chirality of quantum materials as an externally tunable reagent — bridging the chiral anomaly in momentum space with enantioselective chemistry in real space.

The potential for connecting chirality as a quantum number to other chiral phenomena across disciplines, including the asymmetry of matter and antimatter and the homochirality of life, brings topological materials to the fore [8].

Updated References:

M. G. Vergniory et al., Science 2022, 376, 6595. P. Narang, C. A. C. Garcia, C. Felser, Nat. Mater. 2021, 20, 293. J. Gooth et al., Nature 2017, 547, 324. J. Gooth et al., Nature 2019, 575, 315. D. M. Nenno et al., Nat. Rev. Phys. 2022, 2, 682. B. Bradlyn et al., Science 2016, 353, aaf5037. N. B. M. Schröter et al., Science 2020, 369, 179. C. Felser, J. Gooth, arXiv:2205.05809. Y. Gao et al., Berry flux control enables selectivity switching in electrocatalytic CO₂ reduction by chiral antiferromagnets, Manuscript submitted, 2025. Patent Application, Magnetic Field-Controlled Asymmetric Catalysis with Magnetic Topological Materials, Felser et al., 2025.