Theoretical study of high-speed and low-power-consumption MRAM devices using cone magnetization thin films

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K17509
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Applied materials
• Research Institution: National Institute of Advanced Industrial Science and Technology
• Principal Investigator: Matsumoto Rie 国立研究開発法人産業技術総合研究所, エレクトロニクス・製造領域, 主任研究員 (10635303)
• Research Collaborator: IMAMURA hiroshi ; ARAI Hiroko
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: MRAM / スピントルク / 電圧トルク / 垂直磁化 / コーン磁化 / 一軸磁気異方性

Outline of Final Research Achievements

Magnetoresistive random access memories (MRAMs) for the replacement of SRAMs and DRAMs are designed in this project. First, we proposed a spin-transfer torque (STT) MRAM device where high-speed and low-power consumption writing is enabled by the second-order uniaxial magnetic anisotropy in a recording layer.
The　voltage-torque (VT) MRAMs are also attracting an attention because of its low-power-consumption writing compared with STT-MRAMs. Here we proposed a VT-MRAM device having a conically magnetized recording layer and an elliptic cylinder shape which does not require the external magnetic field for writing operations. We also proposed a VT-MRAM device which does not require the voltage pulse to be turned off at around half-period of precessional motion of magnetization, and it can be realized by the energy dissipation through the damping torque.

Free Research Field

スピントロニクス

Academic Significance and Societal Importance of the Research Achievements

二次の垂直磁気異方性をもつ記録層の採用により、書き込みに必要な電流を上げずに熱擾乱耐性を上昇できる上に、バイアス電流の印加により現れるコーン磁化を経由させることで高速書き込みが可能になるという基本原理を発見できた。また外部磁界を必要としない電圧書込み型MRAM素子によって高記録密度化と低コスト化が期待される。電圧パルス時間幅の許容範囲が広いMRAM素子は、電圧源および記録層磁化の歳差時間のバラツキがあっても高い信頼性での電圧書き込みを可能にするものである。本研究の成果によって、SRAMおよびDRAMを不揮発性のMRAMで置き換えることが可能となり、IT 機器の大幅な省エネ化が期待される。