Dichotomy in ultrafast atomic dynamics as direct evidence of polaron formation in manganites

Ultrafast interactions between electrons and the lattice of correlated materials can now be accessed with a new electron diffraction method. Knowing how electrons interact with the lattice as they travel through a material is crucial for understanding properties such as electrical conductivity. A team led by Yimei Zhu at Brookhaven National Laboratory showed that ultrahigh-energy electron diffraction can be used to quantitatively follow changes in the crystal structure and electronic system of a layered manganite on picosecond timescales, unveiling strong evidence for the formation of polarons — a quasiparticle that arises from strong electron-lattice interactions. This technique reveals the important role of electron-lattice interactions in doped magnanites, and could be used to study such interactions in a range of correlated materials.