Switchable voltage control of the magnetic coercive field via magnetoelectric effect

Switchable voltage modulation of the magnetic properties is reported in different multiferroic bilayers with magnetic films grown on pre-poled ferroelectric substrates, based on the magneto-optical Kerr effect observations. The dynamic voltage control of the magnetic coercive field (H_c) is dependent not only on the materials properties of each ferroic layer, but also on the bias voltage history. The H_c versus electric field behaviors essentially track the dependence of the piezostrains of the substrates on the bias voltage. The observations demonstrate that H_c in such multiferroic bilayers can be controlled by voltage via strain-mediated magnetoelectric coupling and that the H_c change is not an artifact due to a heating effect.