Why is Mn charge ordered and AFM coupled in YBaMn2O5?

Synthesis conditions to obtain single-phase YBaMn 2 O 5 are reported and its crystal structure refined from neutron powder diffraction data collected between 25 and 600 ​°C in the paramagnetic state. The structure parameters are used to reason why the phase maintains ordered ionic charges of Mn instead of mixing them at an elevated temperature, why this Mn 2+ and Mn 3+ ordering is of the checkerboard type in all three dimensions, and why these ions would couple antiferromagnetic upon cooling. • Synthesis of single-phase YBaMn 2 O 5 perovskite of precise oxygen content. • Crystal structure by neutron powder diffraction between 25 and 600 ​°C. • Persistent 3-dimensional checkerboard charge order of Mn II and Mn III . • Calculated orbital energies suggest antiferromagnetic coupling of spins. • Calculated orbital energies and lack of thermally induced mixing.