Abstract
An elastic Ising model for CoMnO6 chain is proposed to explain the ferroelectricity induced by collinear magnetic order in Ca3CoMnO6, and then a mean-field theory with interchain spin interactions based on this model is developed. With inclusion of the dynamics of polarization domains at finite temperature, we address the rationality of our theory by the good agreement of the calculated electric polarization and dielectric susceptibility with the reported data on Ca3Co2−xMnxO6 x0.96 Y. J. Choi, H. T. Yi, S. Lee, Q. Huang, V. Kiryukhin, and S.-W. Cheong, Phys. Rev. Lett. 100, 047601 2008, a typical diatomic Ising spin chain system, while the predicted magnetic susceptibility shows some difference from experiment, the reason of which is discussed.