Fig. 1: Crystal structure, basis vectors and symmetry of Ba3Er(BO3)3.
From: Realization of two-sublattice exchange physics in the triangular lattice compound Ba3Er(BO3)3
a Crystal structure of Ba3Er(BO3)3 viewed along the c-axis, showing the superexchange pathways between the Er3+ ions. The magenta and purple atoms are the 2a and 4b Er sites, large light green atoms are Ba, small red atoms are O, and small dark green atoms are B. The colored arcs indicate the different O-B-O angles in the two exchanges (black arcs for J2a and red/blue arcs for J4b. b Crystal structure viewed along the a-axis, showing the hexagonal layers of Er atoms, separated by layers of Ba, B, and O atoms). c Symmetry operations of the two Er sites. The symmetry operations 21, C3, and M correspond to a 180-degree screw axis in the z-direction, a three-fold rotation about the z-axis, and a mirror plane, respectively. The two colors indicate the two Wyckoff positions occupied by the Er3+ atoms in Ba3Er(BO3)3.
