Using resonant X-ray spectroscopies combined with density functional calculations, we find an asymmetric bi-axial strain-induced d-orbital response in ultra-thin films of the correlated metal LaNiO3 which are not accessible in the bulk. The sign of the misfit strain governs the stability of an octahedral "breathing" distortion, which, in turn, produces an emergent charge-ordered ground state with an altered ligand-hole density and bond covalency. Control of this new mechanism opens a pathway to rational orbital engineering, providing a platform for artificially designed Mott materials.
@article{arxiv.1008.1373,
title = {Asymmetric orbital-lattice interactions in ultra-thin correlated oxide films},
author = {J. Chakhalian and J. M. Rondinelli and Jian Liu and B. A. Gray and M. Kareev and E. J. Moon and N. Prasai and J. L. Cohn and M. Varela and I. C. Tung and M. J. Bedzyk and S. G. Altendorf and F. Strigari and B. Dabrowski and L. H. Tjeng and P. J. Ryan and J. W. Freeland},
journal= {arXiv preprint arXiv:1008.1373},
year = {2011}
}