Fig. 1: Lattice and electric-quadrupolar coupling and ordering.
From: Spectroscopic signatures and origin of hidden order in Ba2MgReO6
a–c The lattice deformations (dθ) and charge quadrupoles (qθ) with symmetry θ = x2−y2, z2 and xy, respectively. The blue and orange lobes of qθ correspond to regions with excess and reduced electronic charge, respectively. d, e Below Tq, BMRO develops a simultaneous long-range order of the local distortion \({d}_{\theta }^{{{{\bf{k}}}}}\) and electric quadrupoles \({q}_{\theta }^{{{{\bf{k}}}}}\). d The θ = x2−y2 component exhibits an antiferroic order with a k = [001] propagation vector. e The θ = z2 component displays ferroic, k = [000] arrangement.
