Figure 1. Crystal and magnetic structures of AgCrSe₂.

(a) R3m crystal structure of AgCrSe₂. Ag, Cr and Se atoms are drawn in light blue, green and pink, respectively. Coordination polyhedra, octahedral for Cr and tetrahedral for Ag, are also shown. (b) illustrates the compact CrSe₂ layer on which is superimposed the energy map of the effective potential surrounding Ag⁺ in its tetrahedron, following¹⁴. O indicates octahedral (empty) sites. α and β label the two Ag⁺ triangular sublattices, full and empty, respectively in the R3m structure. The long-wavelength cycloidal magnetic ordering below T_N = 55 K is shown in (c) in the ab plane, the coupling between planes being antiferromagnetic.