Atomic motions untangled

The pursuit of capturing motion in a movie bears an obvious fascination irrespective of the time scales involved. In the atomic and molecular world where the masses are so light and the distances small the relevant time scale shifts to the subpicosecond range and the motions become frantic especially for larger molecular systems. In the material class of strongly correlated electron materials the intricate balance of competing structural, magnetic and charge interactions complicates the picture when it comes down to disentangle the coupled processes. In order to advance the understanding of the underlying correlations in these materials current efforts focus on the interaction of the atomic, electronic, and magnetic subsystems on their relevant time scales. In particular, femtosecond x-ray or electron diffraction received considerable attention in the recent past because they enable direct access to the evolving atomic and electronic structure. Here, we study specific lattice modulations coupled to the melting of charge and orbital order in a manganite by means of femtosecond x-ray diffraction. By using a carefully chosen set of reflections combined with structure factor calculations we are able to identify the involved atomic motions.

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