Charge order fluctuations in the cuprate superconductor Nd2-xCexCuO4 measured by ultra-high-resolution RIXS

Monday, April 9, 2018 - 2:30pm

Charge order has now been ubiquitously observed in cuprate high-temperature superconductors. However, it remains unclear if the charge order is purely static or whether it also features dynamic correlations. In this talk I will describe a resonant inelastic x-ray scattering (RIXS) experiment on the electron-doped cuprate Nd2−xCexCuO4 that demonstrates the existence of fluctuations at the charge order wave vector. Due to recent advances in soft x-ray RIXS instrumentation at the ID32 line of the European Synchrotron Radiation Facility, our new RIXS data allows us to resolve the energy-momentum structure of the charge order and its relationship with magnetism. First, upon cooling, we observe a softening in the electronic response, which has been predicted to occur for a “d-wave” charge order in electron-doped cuprates. Second, at low temperatures, the energy range of these fluctuations coincides with that of the dispersive magnetic modes known as paramagnons. Third, measurements where the polarization of the scattered photon is resolved indicate that the charge fluctuations also involve spin-flip processes. Overall, our findings suggest an unavoidable coupling between magnetic and charge-order fluctuations in the cuprates, regardless of the material’s family. E. H. da Silva Neto, et al. in preparation (2018).

106 Stanley Hall
University of California, Davis