Dynamic Charge Stripes in La2-xSrxNiO4 Detected by Inelastic Neutron Scattering

Dmitry Reznik (University of Colorado-Boulder)

La2-xSrxNiO4 is interesting primarily because of stripe order, characterized by electronic phase separation into domains of charge-poor antiferromagnetic stripes separated by charge rich domain boundaries. Whereas static stripes can be easily detected by diffraction, dynamic or fluctuating stripes have been elusive despite their extreme scientific interest due to their possible role in high temperature superconductivity. A lot of work has focused on measuring magnetic fluctuations that may be associated with dynamic stripes, but the charge component of dynamic stripes remains mostly unexplored. Recently, we developed a novel approach to measuring the spectrum of dynamic charge stripes by inelastic neutron scattering by tracking dynamic polaron-like lattice distortions at the charge stripe ordering wavevector. We found that dynamic charge stripe signal is most prominent just above the charge stripe ordering temperature of 241K. It disappears below the magnetic ordering temperature and at very high temperatures. The charge fluctuation spectrum from low energies up to is narrow in q and broad in energy, which is totally different from phonons. I will present these results obtained at the SNS, HFIR, and Saclay and will discuss other properties of dynamic charge stripes such as their interlayer modulation, interplay with magnetic stripes, and interaction with phonons.

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