Electric-field control of a magnetic phase transition in Ni

We report on the electric-field tuning of a magnetic phase transition temperature (TL) in multiferroic Ni3V2O8 thin films. The simultaneous magnetic and ferroelectric transition in Ni3V2O8 exhibits a clear dielectric anomaly; we monitored TL under applied electric and magnetic fields using dielectric measurements. The transition temperature increases by 0.2 K ± 0.05 K when the sample is biased approximately 25 MV/m compared to zero bias. This electric-field control of the magnetic transition can be qualitatively understood using a mean-field model incorporating a tri-linear coupling between the magnetic order parameters and spontaneous polarization. The shape of the electric field-temperature phase boundary is consistent with the proper order parameter for the multiferroic phase in Ni3V2O8 being a linear combination of the magnetic and ferroelectric correlation functions