Engineering Electronic Chirality: From Kramers Nodal Line Metals to Measured Electron-Chirality Density

Structurally chiral quantum materials could find applications in novel interconnects and magnetic memory devices. However, key scientific challenges remain, including the creation of homochiral thin films and the quantitative observation and control of quasiparticle chirality for novel magnetoelectric effects. In this talk, I will present two recent results that directly address these obstacles.

First, I discuss our discovery of Kramers nodal-line metals in 3R transition-metal dichalcogenides [1]. Using micro-ARPES and ab initio theory, we identify octdong and spindle-torus Fermi surfaces that emerge when Kramers nodal lines cross the Fermi level. These materials lie only one symmetry-breaking step away from structurally chiral Kramers–Weyl semimetals, positioning them as ideal parent phases from which homochiral thin films may be engineered via strain. This establishes a practical route toward structurally chiral electronic states required for chiral interconnects.

Second, I present our direct quantification of quasiparticle chirality in a chiral topological semimetal. Through high-resolution spin-ARPES, we resolve momentum-dependent deviations from perfect Weyl spin–momentum locking, extracting experimental values of the electron-chirality density. These deviations reveal how real materials depart from the ideal Weyl limit and provide crucial guidance for engineering enhanced Edelstein responses, with potential applications in field-free switching of memory devices with perpendicular magnetic anisotropy.

[1] G. Domaine et al., Tunable Octdong and Spindle-Torus Fermi Surfaces in Kramers Nodal Line Metals, Nature Communications 10.1038/s41467-025-66284-9 , arXiv:2503.08571