A combined neutron and x-ray diffraction study of TbBaFe2O5 reveals a rare checkerboard to charge ordering transition. TbBaFe2O5 is a mixed valent compound where Fe2+/Fe3+ ions are known to arrange into a stripe charge-ordered state below TV = 291 K, that consists of alternating Fe2+/Fe3+ stripes in the basal plane running along the b direction. Our measurements reveal that the stripe charge-ordering is preceded by a checkerboard charge-ordered phase between TV < T < T* = 308 K. The checkerboard ordering is stabilized by inter-site coulomb interactions which give way to a stripe state stabilized by orbital ordering.
@article{arxiv.1210.7228,
title = {Checkerboard to Stripe Charge Ordering Transition in TbBaFe2O5},
author = {D. K. Pratt and S. Chang and W. Tain and A. A. Taskin and Yoichi Ando and J. L. Zarestky and A. Kreyssig and A. I. Goldman and R. J. McQueeney},
journal= {arXiv preprint arXiv:1210.7228},
year = {2013}
}