Robustness of Voltage-induced Magnetocapacitance

Hideo Kaiju; Takahiro Misawa; Taro Nagahama; Takashi Komine; Osamu Kitakami; Masaya Fujioka; Junji Nishii; Gang Xiao

doi:10.1038/s41598-018-33065-y

Robustness of Voltage-induced Magnetocapacitance

Sci Rep. 2018 Oct 2;8(1):14709. doi: 10.1038/s41598-018-33065-y.

Authors

Hideo Kaiju¹, Takahiro Misawa², Taro Nagahama³, Takashi Komine⁴, Osamu Kitakami⁵, Masaya Fujioka², Junji Nishii², Gang Xiao⁶

Affiliations

¹ Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido, 001-0020, Japan. kaiju@es.hokudai.ac.jp.
² Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido, 001-0020, Japan.
³ Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido, 060-8628, Japan.
⁴ Graduate School of Science and Engineering, Ibaraki University, Hitachi, Ibaraki, 316-8511, Japan.
⁵ Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi, 980-8577, Japan.
⁶ Department of Physics, Brown University, Providence, RI, 02912, USA.

Abstract

One of the most important achievements in the field of spintronics is the development of magnetic tunnel junctions (MTJs). MTJs exhibit a large tunneling magnetoresistance (TMR). However, TMR is strongly dependent on biasing voltage, generally, decreasing with applying bias. The rapid decay of TMR was a major deficiency of MTJs. Here we report a new phenomenon at room temperature, in which the tunneling magnetocapacitance (TMC) increases with biasing voltage in an MTJ system based on Co₄₀Fe₄₀B₂₀/MgO/Co₄₀Fe₄₀B₂₀. We have observed a maximum TMC value of 102% under appropriate biasing, which is the largest voltage-induced TMC effect ever reported for MTJs. We have found excellent agreement between theory and experiment for the bipolar biasing regions using Debye-Fröhlich model combined with quartic barrier approximation and spin-dependent drift-diffusion model. Based on our calculation, we predict that the voltage-induced TMC ratio could reach 1100% in MTJs with a corresponding TMR value of 604%. Our work has provided a new understanding on the voltage-induced AC spin-dependent transport in MTJs. The results reported here may open a novel pathway for spintronics applications, e.g., non-volatile memories and spin logic circuits.