Effect of nonmagnetic substituent Zn on the phase competition and multiferroic properties in the polar magnet Fe2Mo3O8

The polar magnet, Fe2Mo3O8 (FMO), with linear magnetoelectric (ME) coupling, is a promising candidate for multiferroic applications in advanced spin devices. However, a giant magnetic bias (Hb) is needed for optimizing the inverse ME effect, i.e., electric field (E) modulation of magnetization (M), which is still a core issue. Herein, we utilize the chemical doping route to enhance the sensitivity of controlling the competitive magnetic interactions and/or multiferroic phases by means of introducing nonmagnetic Zn2+ ions into FMO crystals. Compared with FMO, the Zn-doped composition (Fe0.95Zn0.05)2Mo3O8 (FZMO) generates three metastable magnetic states in the middle of antiferromagnetic and ferrimagnetic states, along with obvious ferroelectric polarization. The inverse ME effect of FZMO is intact with a relative change of ΔM ≈ 0.06 μB/f.u. responding to an E value of ± 20 kV/cm at 52 K. Most interestingly, the exciting Hb is dramatically dropped to 0.8 T for FZMO from 5.1 T for FMO, which is in favor of the application of ME coupling. It is suggested that the perturbation of magnetic interactions via substituting specific sites by nonmagnetic ions plays a key role in decreasing the exciting Hb without deteriorating the inverse ME coupling in this polar M2Mo3O8 family.