# Coupled dynamics of long-range and internal spin cluster order in Cu$_{2}$OSeO$_{3}$

## TL;DR

This study investigates the coupled spin and lattice dynamics in Cu$_2$OSeO$_3$, revealing a separation of order parameter dynamics related to long-range and internal spin cluster order using time-resolved Raman spectroscopy.

## Contribution

It provides new insights into the double order parameter dynamics in a cluster magnet, highlighting the separation of disordering processes in a Mott insulator.

## Key findings

- Observation of multiple ps-decade spin-lattice relaxation dynamics
- Evidence for separation of order parameter dynamics
- Demonstration of double order parameter dynamics in a molecular crystal

## Abstract

Cu$_4$ triplet clusters form the relevant spin entity for the formation of long-range magnetic order in the cluster magnet Cu$_2$OSeO$_3$. Using time-resolved Raman spectroscopy, we probed photoinduced spin and lattice dynamics in this Mott insulator. Multiple ps-decade spin-lattice relaxation dynamics is observed, evidencing a separation of the order parameter dynamics into disordering of long-range and internal spin cluster order. Our study exemplifies the double order parameter dynamics of generalized molecular crystals of charge, spin, and orbital nature.