Comparative Electronic Structures of the Chiral Helimagnets Cr_1/3NbS₂ and Cr_1/3TaS₂

Magnetic materials with noncollinear spin textures are promising for spintronic applications. To realize practical devices, control over the length and energy scales of such spin textures is imperative. The chiral helimagnets Cr_1/3NbS₂ and Cr_1/3TaS₂ exhibit analogous magnetic-phase diagrams with different real-space periodicities and field dependence, positioning them as model systems for studying the relative strengths of the microscopic mechanisms giving rise to exotic spin textures. Although the electronic structure of the Nb analogue has been experimentally investigated, the Ta analogue has received far less attention. Here, we present a comprehensive suite of electronic structure studies on both Cr_1/3NbS₂ and Cr_1/3TaS₂ using angle-resolved photoemission spectroscopy and density functional theory. We show that bands in Cr_1/3TaS₂ are more dispersive than their counterparts in Cr_1/3NbS₂, resulting in markedly different Fermi wavevectors. The fact that their qualitative magnetic phase diagrams are nevertheless identical shows that hybridization between the intercalant and host lattice mediates the magnetic exchange interactions in both of these materials. We ultimately find that ferromagnetic coupling is stronger in Cr_1/3TaS₂, but larger spin-orbit coupling (and a stronger Dzyaloshinskii-Moriya interaction) from the heavier host lattice ultimately gives rise to shorter spin textures.