Short-range ferromagnetic correlations in the spin-chain compound Ca3CoMnO6

Abstract

Unusual short-range ferromagnetic (FM) correlations, which can be understood in terms of a Griffiths-like singularity, have been illustrated in the spin-chain compound Ca${}_{3}$CoMnO${}_{6}$ by systematic magnetization measurements. First, these FM correlations can be dramatically suppressed by a small stoichiometric mismatch of Co/Mn atoms. Second, these FM correlations develop at ${T}_{\mathrm{G}}$ $=$ \ensuremath{\sim}125 K, a temperature much higher than the ordering temperature of ${T}_{\mathrm{N}}$ $=$ \ensuremath{\sim}13 K, and survive in magnetic fields of more than 2 T, indicating their robustness. This feature is quite different from the general case---a Griffiths-like anomaly was usually observed in very low magnetic fields and, in many cases, was suppressed in a field of several kilo-oersted.