3:1 magnetization plateau and suppression of ferroelectric polarization in an Ising chain multiferroic

Ferroelectric Ising chain magnet Ca₃Co_2-xMn _xO₆ (x≃0.96) was studied in magnetic fields of up to 33 T. Magnetization and neutron-scattering measurements reveal successive metamagnetic transitions from the zero-field ↑↑↓↓ spin configuration to the ↑↑↑↓ state with a broad magnetization plateau, and then to the ↑↑↑↑ state. The absence of hysteresis in these plateaus reveals an intriguing coupling between the intrachain state and the three-dimensional geometrically frustrated magnetic system. Inversion symmetry, broken in the ↑↑↓↓ state, is restored in the ↑↑↑↓ state, leading to the complete suppression of the electric polarization driven by symmetric superexchange.