Coupling between dynamic magnetic and charge-order correlations in the cuprate superconductor Nd$_{2-x}$Ce$_{x}$CuO$_4$

TL;DR

This study reveals a coupling between dynamic magnetic and charge-order correlations in the electron-doped cuprate Nd$_{2-x}$Ce$_{x}$CuO$_4$, showing softening of electronic response and spin-flip excitations at the charge order wave vector.

Contribution

It provides experimental evidence of the interaction between magnetic and charge fluctuations in cuprates using resonant inelastic x-ray scattering.

Findings

Observation of dynamic charge correlations at the charge order wave vector.

Softening of electronic response upon cooling consistent with d-wave charge order.

Dynamic response involves spin-flip excitations, indicating coupling with magnetic modes.

Abstract

Charge order has now been observed in several cuprate high-temperature superconductors. We report a resonant inelastic x-ray scattering experiment on the electron-doped cuprate Nd$_{2-x}$Ce$_{x}$CuO$_4$ that demonstrates the existence of dynamic correlations at the charge order wave vector. 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. At low temperatures, the energy range of these excitations coincides with that of the dispersive magnetic modes known as paramagnons. Furthermore, measurements where the polarization of the scattered photon is resolved indicate that the dynamic response at the charge order wave vector primarily involves spin-flip excitations. Overall, our findings indicate a coupling between dynamic magnetic and charge-order correlations in the cuprates.