Robustness of Voltage-induced Magnetocapacitance

• Published in: Scientific reports Vol. 8; no. 1; pp. 14709 - 10
• Main Authors: Kaiju, Hideo, Misawa, Takahiro, Nagahama, Taro, Komine, Takashi, Kitakami, Osamu, Fujioka, Masaya, Nishii, Junji, Xiao, Gang
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 02.10.2018; Nature Publishing Group UK
• Subjects: Approximation; Misfit dislocations; Voltage
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-018-33065-y

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 Co Fe B /MgO/Co Fe B . 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.