Spiral-induced anomalous Hall effect from odd-parity spin-nodal lines

Spin spirals represent a fundamental class of noncollinear yet coplanar magnetic structures that give rise to diverse emergent phenomena through their coupling to itinerant electrons. We investigate metallic systems with spin spirals and uncover an unconventional anomalous Hall effect (AHE) induced by spiral magnetism in both noncentrosymmetric and centrosymmetric crystals. The spin spiral generates odd-parity spin splitting with polarization perpendicular to the helical plane, forming spin-nodal lines in the electronic structure. In the presence of spin-orbit coupling, finite magnetization opens gaps at these nodal lines, resulting in the Berry curvature concentrated near the gaps and a distinctive AHE. We identify the interplay among the spin-orbit coupling, helical plane orientation, and magnetization direction as the key ingredient for this spiral-induced AHE. Our results establish a broadly applicable mechanism for anomalous Hall responses across a wide range of materials hosting spin spirals.