Figure 1: Most relevant crystal distortions and spin configurations in orthoferrites and orthochromites.
From: Improper electric polarization in simple perovskite oxides with two magnetic sublattices
(a) Sketch of the perovskite structure in the 20-atom cell used in our calculations of GdFeO3 and GdCrO3. (b) Definition of the orthorhombic (a, b and c) and pseudo-cubic (apc, bpc and cpc) axes. The rare-earth and transition-metal atoms are numbered. (c) Basic spin arrangements considered in this study (note that ‘F’ stands for ferromagnetic order). We indicate them for the Fe/Cr sublattice, those of the rare-earth sublattice being analogous. Sketches of atomic distortions discussed in the text: (d) in-phase O6 rotations, (e) antiphase O6 rotations and (f) anti-polar motions. In f, the larger arrows correspond to an X-point anti-polar modulation vector, while the smaller arrows indicate an R-point modulation (see text).
