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Theoretical study of interface engineering for magnetic tunnel junction application
http://hdl.handle.net/10076/0002001694
http://hdl.handle.net/10076/000200169417c9a0b0-3cbf-48c5-bbc7-807eacf8f696
| 名前 / ファイル | ライセンス | アクション |
|---|---|---|
2025DE0908.pdf (17.1 MB)
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| アイテムタイプ | 学位論文 / Thesis or Dissertation(1) | |||||||
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| 公開日 | 2026-01-26 | |||||||
| タイトル | ||||||||
| タイトル | Theoretical study of interface engineering for magnetic tunnel junction application | |||||||
| 言語 | en | |||||||
| 言語 | ||||||||
| 言語 | eng | |||||||
| 資源タイプ | ||||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_db06 | |||||||
| 資源タイプ | doctoral thesis | |||||||
| アクセス権 | ||||||||
| アクセス権 | open access | |||||||
| アクセス権URI | http://purl.org/coar/access_right/c_abf2 | |||||||
| 著者 |
Yosephine Novita Apriati
× Yosephine Novita Apriati
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| 著者（ヨミ） | ||||||||
| 別名 | ヨセフィン ノフイタ アプリアティ | |||||||
| 言語 | ja-Kana | |||||||
| 抄録 | ||||||||
| 内容記述タイプ | Abstract | |||||||
| 内容記述 | The magnetic tunnel junctions (MTJs) are the key component of magnetoresistive randomaccess memory (MRAM). The development of next-generation MRAM critically depends on the design of MTJ materials, which consist of ferromagnetic (FM) layers and thin insulator barrier sandwiched between them. Specifically in spin-transfer-torque MRAM (STT-MRAM), the commercially adopted MTJ design typically consists of CoFeB/MgO/CoFeB, which exhibits both high tunneling magnetoresistance (TMR) and perpendicular magnetocrystalline anisotropy (PMA), the two key parameters for MTJ performance. Although, a major problem in this Fe/MgO-based MTJs for the next-generation MRAM lies in the high energy required to control the switching mechanism at the FM free-layer. To overcome the issues, various strategies, e.g., interface modifications, insulating barrier substitutions, introducing heavy metals, or using an external voltage, have been carried to improve the energy efficiency of the switching mechanism. Nevertheless, clear guidelines for achieving efficient switching are still needed. In this study, a theoretical investigation of Fe/MgO-based MTJ designs, focusing on interface modifications is conducted as a pathway toward enhancing switching efficiency. Chapter One of this thesis presents the background and purpose of the study. It includes a description of the memory hierarchy in electronic systems, a review of previous efforts to address the trade-off between thermal stability and magnetic damping in order to achieve long memory retention while maintaining a low-energy switching mechanism in perpendicular MTJs, and a discussion of the recently proposed concept of using an external voltage to facilitate easy switching. Chapter Two systematically presents the theoretical framework and computational methods employed as the primary tools throughout this study. This includes detailed explanations of density functional theory calculations and the theorems used to support post-processing analyses. In chapter three, the issues related to the trade-off relationship between PMA and magnetic damping is discussed. To achieve an efficient switching in a low dimensional MTJs, nearly 1X nm, the thermal stability which critically contributes to long-term data retention, is essential and directly depends on PMA. However, designs that achieve high PMA, often through the insertion of heavy metals at the interface, is followed by the large magnetic damping, as they share the same spin-orbit coupling origin. The magnetic damping play role to control the lose in energy and settle the magnetization back to the stable state after being disturbed. This chapter demonstrates that interface engineering through the deliberate introduction of holes and electrons can provide an effective pathway to simultaneously achieve large PMA and low magnetic damping. In Chapter four, an alternative approach to achieving efficient switching mechanism via the application of an external electric field is explored. The external electric field acts as an energy pulse that temporarily lowers the magnetization energy barrier, facilitating magnetization precession to the opposite direction through spin-transfer torque (STT). The physical origin of the voltage-assisted magnetic anisotropy primarily related to the modification of the occupied states and electric-field-induced changes in magnetic dipole moments. In heterolayer systems such as the Fe/MgO interface, however, the broken symmetry due to the contrasting electrostatic potential at the interface may lead to the change in magnetocrystalline anisotropy can not be ignored. This chapter further confirms how interface modifications, mediated by Rashba effects, that is driven by both broken inversion symmetry and spin-orbit coupling contribute to the enhanced voltage-assisted magnetic anisotropy, thereby promoting the switching efficiency. Chapter five finally remarks the conclusion of the work and a review for the future prospect of the study in contributing to the advance development ot MTJs in STT-MRAM. |
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| 言語 | en | |||||||
| 内容記述 | ||||||||
| 内容記述タイプ | Other | |||||||
| 内容記述 | 本文/Graduate School of Engineering Division of Material Science | |||||||
| 内容記述 | ||||||||
| 内容記述タイプ | Other | |||||||
| 内容記述 | 93p | |||||||
| 書誌情報 |
発行日 2025-09-25 |
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| フォーマット | ||||||||
| 内容記述タイプ | Other | |||||||
| 内容記述 | application/pdf | |||||||
| 著者版フラグ | ||||||||
| 出版タイプ | VoR | |||||||
| 出版タイプResource | http://purl.org/coar/version/c_970fb48d4fbd8a85 | |||||||
| その他の言語のタイトル | ||||||||
| その他のタイトル | 磁気トンネル接合素子開発に向けた界面工学に関する理論的研究 | |||||||
| 言語 | ja | |||||||
| 出版者 | ||||||||
| 出版者 | 三重大学 | |||||||
| 出版者（ヨミ） | ||||||||
| 値 | ミエダイガク | |||||||
| 学位名 | ||||||||
| 学位名 | 博士(工学) | |||||||
| 学位授与機関 | ||||||||
| 学位授与機関識別子Scheme | kakenhi | |||||||
| 学位授与機関識別子 | 14101 | |||||||
| 学位授与機関名 | 三重大学 | |||||||
| 学位授与年月日 | ||||||||
| 学位授与年月日 | 2025-09-25 | |||||||
| 学位授与番号 | ||||||||
| 学位授与番号 | 甲工学第2344号 | |||||||
| 資源タイプ（三重大） | ||||||||
| 値 | Doctoral Dissertation / 博士論文 | |||||||
