[19a-331-7~12] 10.3 スピンデバイス・磁気メモリ・ストレージ技術

▼ [19a-331-10] Tunnel Magnetocapacitance in Single-layered Fe/MgF₂ Granular Films

〇Robin Msiska¹、Shusaku Honjo²、Yuki Asai²、Masashi Arita²、Atsushi Tsurumaki-Fukuchi²、Yasuo Takahashi²、Norihisa Hoshino³、Tomoyuki Akutagawa³、Osamu Kitakami³、Masaya Fujioka¹、Junji Nishii¹、Hideo Kaiju¹ (1.RIES, Hokkaido Univ.、2.IST, Hokkaido Univ.、3.IMRAM, Tohoku Univ.)

キーワード：Magnetocapacitance, Granular Films, Nanostructures

Magnetocapacitance (MC) effects lead to some appealing spin-based phenomena such as frequency-dependent spin transport and spin capacitance, which are crucial for spintronic devices. MC offers attractive prospects for materials research and device applications such as high-frequency devices and energy storage. Here we report tunnel magnetocapacitance (TMC) in single-layered Fe/MgF₂ granular films. As a result, at 40 Hz, the TMC ratio with 1 kOe reaches 1.45%, which is larger than the value (0.8%) previously reported in two-dimensional (2D) Co/AlF granular films. The TMC ratio reaches up to 2.89% at 30 Hz, which is the highest value ever reported for 2D granular films. A combination of the Debye-Fröhlich (DF) model and the Julliere formula was used to fit the experimental data to theory, and an excellent agreement between the calculated values and the experimental data was obtained. To perfectly fit the data, the conventional DF model was extended to a three-phase model in which three capacitors were introduced. Our findings will give further insight into the exact mechanism of TMC effect in nanogranular films, and will open broader opportunities for device applications, such as magnetic sensors and impedance tunable devices.