Enhancement of giant magnetoelectric effect in Ni-doped CaBaCo4O7

Abstract

The polar ferrimagnet CaBaCo${}_{4}$O${}_{7}$ exhibits the largest magnetic field driven electric polarization change \ensuremath{\Delta}$P$ reported so far in a narrow temperature range. Here, the authors demonstrate that only 2.5% of Ni substitution for Co increases the magnitude of \ensuremath{\Delta}$P$ by about 30%, as well as expanding the temperature range in which the giant \ensuremath{\Delta}$P$ appears down to a low temperature. This is attributable to the switching of the low-temperature zero magnetic field state from a ferrimagnetic to an antiferromagnetic state.