Giant room-temperature magnetocapacitance in Co~(2+) doped SnO_2 dielectric films

摘要

The giant room-temperature magnetocapacitance is reported in the Co~(2+) substitutionally doped SnO_2 film in which the ferromagnetism coexists with the dielectric state. The maximum magnetocapacitance is observed in the Sn_(0.98)Co_(0.02)O_2 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.