Interface-driven magnetocapacitance in a broad range of materials

Triggered by the revival of multiferroic materials, a lot of effort is presently underway to find a coupling between a capacitance and a magnetic field. We show in this paper that interfaces are the right way of increasing such a coupling provided free charges are localized on these two-dimensional defects. Starting from commercial diodes at room temperature and going to grain boundaries in giant permittivity materials and to ferroelectric domain walls, a clear magnetocapacitance is reported which is all the time more than a few per cent for a magnetic field of 90 kOe. The only tuning parameter for such strong coupling to arise is the dielectric relaxation time which is reached on tuning the operating frequency and the temperature in many different materials.