Crystal structure, spin flop transition, and magnetoelectric effect in the honeycomb-lattice frustrated Fe-doped Ni2Mo3O8 antiferromagnets

The magnetoelectric (ME) effect, with the cross coupling between magnetism and electric polarization, provides a new controlling dimension for creating novel information storage devices. Here, we report crystal structure, magnetic field-induced spin flop transition, and ME behaviors of Fe-doped Ni2Mo3O8 by using comprehensive characterization methods of x-ray diffraction, high-angle annular dark-field images, magnetization, specific-heat capacity, dielectric and electric polarization measurements. The Fe/Ni honeycomb lattice is endowed with strong magnetic frustration. Through Fe doping, a metamagnetic spin flop (SF) transition and the related linear magnetoelectric effect are achieved under a lower magnetic field, which is due to the delicate modification of magnetic interactions. Consequently, the maximum direct ME coefficient alpha H (=238 ps m-1) and converse ME coefficient alpha E (=110 ps m-1) were achieved in Ni0.5Fe1.5Mo3O8 at the phase boundary of antiferromagnetic-SF and SF phase, respectively.