[20a-W241-1~12] 10.3 GMR・TMR・磁気記録技術

▲ [20a-W241-10] Large magnetocapacitance effect at room temperature in magnetic tunnel junctions

〇海住 英生¹、武井 将志¹、三澤 貴浩¹、長浜 太郎²、西井 準治¹、Xiao Gang³ (1.RIES Hokkaido Univ.、2.Eng. Hokkaido Univ.、3.Phys. Brown Univ.)

キーワード：Magnetic tunnel junction,Magnetocapacitance effect,Debye-Frohlich model

The frequency dependence of tunneling magnetocapacitance (TMC) in magnetic tunnel junctions (MTJs) is investigated theoretically and experimentally. According to the calculation based on Debye-Fröhlich model combined with Julliere formula, the TMC ratio strongly depends on the frequency and it has the maximum peak at a specific frequency. The calculated frequency dependence of TMC is in good agreement with the experimental results obtained in MgO-based MTJs with a tunneling magnetoresistance (TMR) ratio of 108%, which exhibit a large TMC ratio of 155% at room temperature. This calculation also predicts that the TMC ratio can be as large as about 1000% for a spin polarization of 87%, while the TMR ratio is 623% for the same spin polarization. These theoretical and experimental findings provide a deeper understanding on AC spin-dependent transport in MTJs and will open up wider opportunities for device applications, such as highly sensitive magnetic sensors and impedance-tunable devices.