We report discovery of collinear-magnetism-driven ferroelectricity in the Ising chain magnet
Ca 3 Co 2-x Mn x O 6 (x≈ 0.96). Neutron diffraction shows that Co 2+ and Mn 4+ ions
alternating along the chains exhibit an up-up-down-down (<? format?>↑↑↓↓) magnetic
order. The ferroelectricity results from the inversion symmetry breaking in the↑↑↓↓ spin
chain with an alternating charge order. Unlike in spiral magnetoelectrics where
antisymmetric exchange coupling is active, the symmetry breaking in Ca 3 (Co, Mn) 2 O 6 …

The concept of magnetism-driven ferroelectricity has recently drawn a significant attention in
condensed matter physics and materials science community. Among the simplest model
systems showing this effect are magnetic spiral compounds, and frustrated collinear chain
magnets with alternating charge order. While many experimental realizations of the former
systems exist, no examples of the latter have been reported so far. Herein, we report
discovery of an experimental realization of this model in the Ising chain compound Ca3Co2 …