The authors investigated the structure and properties of GdBaCo2O5.5+δ thin films epitaxially grown on SrTiO3 (001) single crystal substrates. The thin films were found to have a notable remnant magnetization above room temperature, which is much higher than that observed in bulk material. Transmission electron microscopy and x-ray diffraction patterns reveal that phase separation occurs in these films, and the phase responsible for the enhanced ferromagnetic order is a-oriented. The enhanced ferromagnetic order is attributed to the enhanced orbital order of Co3+ in CoO5 pyramids, and the disappearance of ferromagnetic to antiferromagnetic transition is explained the stabilization of higher spin state of Co3+ in CoO6 octahedra.
@article{arxiv.0901.1388,
title = {Enhanced Ferromagnetic Ordering in GdBaCo$_{2}$O$_{5.5+\delta}$ Films on SrTiO3 (001) Substrate},
author = {G. Y. Wang and X. Y. Zhou and R. K. Zheng and Y. M. Hu and H. L. W. Chan and Y. Wang},
journal= {arXiv preprint arXiv:0901.1388},
year = {2009}
}