Magnetic dynamics across the in-field transition in Ca3Co2O6

The discovery of multiple coexisting magnetic phases in the crystallographically homogeneous compound ${\mathrm{Ca}}_{3}{\mathrm{Co}}_{2}{\mathrm{O}}_{6}$ has stimulated ongoing research activity. In recent years the main focus has been on the zero-field-state properties, where exceedingly long timescales have been established. In this study we report a detailed investigation of static and dynamic properties of ${\mathrm{Ca}}_{3}{\mathrm{Co}}_{2}{\mathrm{O}}_{6}$ across the magnetic field induced transition around 3.5 T. This region has so far been practically neglected, while we argue that in some aspects it represents a simpler version of the transition across the $B=0$ state. Investigating the frequency dependence of the ac susceptibility, we reveal that on the high-field side ($Bg3.5$ T) the response corresponds to a relatively narrow distribution of magnetic clusters. The distribution appears very weakly dependent on magnetic field, with an associated energy barrier of around 200 K. Below 3.5 T a second contribution arises, with much smaller characteristic frequencies and a strong temperature and magnetic field dependence. We discuss these findings in the context of intrachain and interchain clustering of magnetic moments.