Evidence of large magneto-dielectric effect coupled to a metamagnetic transition in Yb2CoMnO6

The double perovskite Yb2CoMnO6 has been synthesized with an almost perfect checkerboard arrangement of Co2+ and Mn4+ cations in the B-sublattice of the perovskite cell. It presents an anomaly in the electric capacitance and a strong magneto-dielectric effect at about 40 K whose interplay with the microscopic magnetic behavior has been investigated by means of neutron diffraction, magnetization, pyroelectric, and relative dielectric permittivity measurements. We show that the onset of an E-type antiferromagnetic ordering of Co2+ and Mn4+ moments monitored by neutron diffraction provokes the noticeable jump of the relative dielectric permittivity (∼9%) at about 40 K. It is also shown that this jump can be totally suppressed by application of a magnetic field of μ0H = 5 T. Neutron experiments and magnetic measurements confirm that such a suppression leading to a significant magneto-dielectric effect is driven by a metamagnetic phase transition from the peculiar E-type ordering of 3d moments into a collinear ferromagnetic order. Pyroelectric current measurements do not show any spontaneous electric polarization, so the large dielectric anomaly at zero field cannot be ascribed to a ferroelectric ordering.