Observation of large tunnel magnetocapacitance effect and elucidation of its mechanism

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H01397
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 21060:Electron device and electronic equipment-related
• Research Institution: Keio University
• Principal Investigator: KAIJU Hideo 慶應義塾大学, 理工学部(矢上), 教授 (70396323)
• Co-Investigator(Kenkyū-buntansha): 介川 裕章 国立研究開発法人物質・材料研究機構, 磁性・スピントロニクス材料研究拠点, 主幹研究員 (30462518)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 磁気トンネル接合 / キャパシタンス / 交流インピーダンス特性 / 表面・界面物性 / ナノ構造

Outline of Final Research Achievements

Magnetic tunnel junctions (MTJs), which comprise a thin insulator sandwiched between two ferromagnetic layers, exhibit a high tunnel magnetocapacitance (TMC) effect at room temperature. The TMC effect is a phenomenon in which the capacitance changes with the magnetic field in tunneling systems. In this study, we investigate the frequency characteristics and voltage dependence of TMC effect in MgAlO-based MTJs. As a result, we observe a large TMC effect beyond 400% at room temperature in MgAlO-based MTJs. The observed results can be reasonably explained using Debye-Frolich model calculations combined with the Zhang formula, sigmoid function, parabolic approximation, and spin-dependent drift-diffusion theory. Additionally, the calculation predicts a 1500% TMC in the MTJs when 90% spin polarization is achieved. Our results provide a basis for the development of AC/DC spintronic applications.

Free Research Field

スピントロニクス

Academic Significance and Societal Importance of the Research Achievements

本研究成果は、静的なスピン蓄積と交流電場下のスピンダイナミクスに関する新たな学術的知見を提供するとともに、次世代革新的超高性能磁気センサ・メモリの実現に向けた重要な設計指針を導くと期待できる。