We report the first observation of `orbital truncation rods' -- the scattering arising from the termination of bulk orbital order at the surface of a crystal. The x-ray measurements, performed on a cleaved, single-layered perovskite, La0.5Sr1.5MnO4, reveal that while the crystallographic surface is atomically smooth, the orbital `surface' is much rougher, with an r.m.s. deviation from the average `surface' of ~0.7nm. The temperature dependence of this scattering shows evidence of a surface-induced second order transition.
@article{arxiv.0706.0939,
title = {Surface effects on the orbital order in the single layered manganite La0.5Sr1.5MnO4},
author = {Y. Wakabayashi and M. H. Upton and S. Grenier and J. P. Hill and C. S. Nelson and J. -W. Kim and P. J. Ryan and A. I. Goldman and H. Zheng and J. F. Mitchell},
journal= {arXiv preprint arXiv:0706.0939},
year = {2011}
}