Giant room-temperature magnetocapacitance in Co2+ doped SnO2 dielectric films

The giant room-temperature magnetocapacitance is reported in the Co2+ substitutionally doped SnO2 film in which the ferromagnetism coexists with the dielectric state. The maximum magnetocapacitance is observed in the Sn0.98Co0.02O2 film in which the magnetocapacitance is as large as 0.45 at frequency of 1.0 kHz and saturated magnetic field of ∼6.0 kOe. We experimentally demonstrate that such magnetocapacitance effect correlates with the Co dopant concentration and the existence of oxygen vacancy. The electric polarization response of the oxygen vacancy–Co ion complexes to the magnetic field is attributed to the origin of the magnetocapacitance.