Multiple Magnetoelectric Plateaux in Polar Magnet Fe${}_2$Mo${}_3$O${}_8$

Abstract

The magnetization and electric polarization of a polar antiferromagnet Fe${}_2$Mo${}_3$O${}_8$ are studied up to 66 T for spin-saturation magnetic fields applied along the polar axis. The magnetization process at 1.4 K exhibited multistep structures below the saturation field of 65 T. The electric polarization along the polar axis exhibits a similar multistep behavior with a total change of 1.2 $\mu C/c{\mathrm{m}}^2$. A combined triangular-lattice antiferromagnetic model with strong Ising-type spin anisotropy reproduces this multistep magnetoelectric (ME) effect. The exchange striction mechanism explains the remarkable ME response in the two sub-lattice type-I multiferroic materials. These results and interpretation demonstrate a method for realizing multistage magnetoelectric effects in hybrid spin systems.

10 pages, 5 figures