Magnetodielectric effect and significant magnetoelectric coupling of Co3NiNb2O9 single crystal

A(4)B(2)O(9) (A = Co, Fe, Mn, Ni, B = Nb, Ta) compounds with a corundum-type structure can host multiferroic phenomena and present magnetoelectric coupling to achieve manipulations of their ground states by external fields. High quality Ni-doped Co4Nb2O9 single crystals of Co3NiNb2O9 have been synthesized for the first time using optical floating zone technique. Co3NiNb2O9 exhibits an antiferromagnetic order at 32 K with an easy magnetization axis in the ab plane. Field-dependent magnetizations at 20 K along [100] and [120] directions have a slope change at 6 and 9 kOe, respectively, indicating a spin-flop transition or spin rotation in the ab plane. Temperature dependence of dielectric constants along [100] and [120] directions show a magnetic-field-induced peak near the antiferromagnetic transition, proving a sizable magnetodielectric effect. Pyroelectric currents along [100] and [120] directions also have a divergent behavior near the transition under magnetic fields, manifesting a magnetoelectric coupling effect. The electric polarization along [120] direction reaches 128 mu C/m(2) under a magnetic field of 40 kOe, larger than that in most phases of the A(4)B(2)O(9) system.

Automated summary

Co3NiNb2O9 is a compound with multiferroic properties and magnetoelectric coupling effect, allowing manipulation of its ground state by external magnetic fields. High quality Ni-doped Co4Nb2O9 single crystals were synthesized for the first time, and antiferromagnetic order, magnetodielectric effect, and magnetoelectric coupling effect were observed.