Magnetic dynamics across the in-field transition in Ca3Co2O6

The discovery of multiple coexisting magnetic phases in the crystallographically homogeneous compound Ca3Co2O6 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 Ca3Co2O6 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 (B > 3.5 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.