Real-time manifestation of strongly coupled spin and charge order parameters in stripe-ordered nickelates via time-resolved resonant x-ray diffraction

TL;DR

This study uses time-resolved resonant X-ray diffraction to reveal that spin and charge order parameters in stripe-ordered nickelates are strongly coupled dynamically, with distinct re-orientation timescales despite different energy scales.

Contribution

It demonstrates the real-time coupling and distinct dynamics of spin and charge order parameters in nickelates under non-equilibrium conditions.

Findings

Spin and charge order parameters are dynamically linked.

The spin sector exhibits a longer re-orientation timescale.

The correlation between symmetry-broken states persists during non-equilibrium.

Abstract

We investigate the order parameter dynamics of the stripe-ordered nickelate, La$_{1.75}$Sr$_{0.25}$NiO$_4$, using time-resolved resonant X-ray diffraction. In spite of distinct spin and charge energy scales, the two order parameters' amplitude dynamics are found to be linked together due to strong coupling. Additionally, the vector nature of the spin sector introduces a longer re-orientation time scale which is absent in the charge sector. These findings demonstrate that the correlation linking the symmetry-broken states does not unbind during the non-equilibrium process, and the time scales are not necessarily associated with the characteristic energy scales of individual degrees of freedom.