On and off Resonant X-ray Diffraction Crytallography on a magnetically taylored manganite superlattice.

Aiming at designing novel magnetic materials, we are coordinating theoretical calculations and fabrication of heterostructure systems magnetically tailored by strain engineering. Controlled strain can be applied on magnetic films epitaxially grown on crystalline substrate. We have grown films of doped manganites that are notoriously sensitive to external fields but are difficult to model because of the random positions of dopants and their inherent strongly correlated effects. As a start, a realistic atomic structure is necessary to predict the magnetic properties but ab initio structures have proved to be difficult to calculate. With this proposal, we aim at determining the crystallographic structure of a manganite multilayer unit cell, in particular determining as accurately as possible the oxygen positions that determine the magnetic couplings between Mn atoms. On and off resonant diffraction methodologies are combined to achieve this challenging thin film crystallography study.