Magnetization reversal with electric field applied in antiferromagnetic dielectric with two dimensional spin arrangement / ferromagnetic multilayer

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K06358
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Electronic materials/Electric materials
• Research Institution: Nihon University
• Principal Investigator: IWATA Nobuyuki 日本大学, 理工学部, 教授 (20328686)
• Co-Investigator(Kenkyū-buntansha): 永田 知子 日本大学, 理工学部, 助教 (00733065) ; 高瀬 浩一 日本大学, 理工学部, 教授 (10297781)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 電気磁気効果 / Cr2O3 / 交換バイアス磁場 / 電界効果型不揮発性磁気メモリ / 酸化物薄膜 / スパッタ法

Outline of Final Research Achievements

Iron Fe(2%) doped Cr2O3 thin films were deposited on YAlO3(YAO)(001) substrate to reduce lattice mismatch. Comparing the results of Cr2O3 films grown on YAO and sapphire substrates, the size of grains was 3.7 and 1.4 times larger, and the area of trenches was reduced down to 48 and 51%, respectively.
Pt(1.5nm)/Co(0.6nm)/Pt(0.5nm)/Cr2O3 multilayer was grown on YAO substrate. Magnetization curves was measured between 50 and 300K normal to the surface. The maximum exchange bias field (HEB) was observed at 160K. The value of HEB was 620Oe, which is the highest value in the multilayers using r-oriented Cr2O3 thin films. The HEB gradually decreased with temperature increased and became zero around Neel temperature 307K of Cr2O3.

Free Research Field

電気電子材料、新機能性薄膜材料、スパッタ法、PLD法、マルチフェロイック材料

Academic Significance and Societal Importance of the Research Achievements

本研究では電流によるジュール損失が極小の不揮発性磁気メモリを提案する。電界印加による磁化反転には、10nm×10nmのセル面積で、書込遅延100ps以下、読出し遅延1ns以下が予想できる。c面配向Cr2O3薄膜を用いた積層膜で同様な研究報告がある。しかし、双晶を含有し反強磁性(AFM)単一ドメインを得られないことから、電界印加のみによる磁化反転は未だ報告がない。AFM単一ドメインが得られるr面配向Cr2O3を用いて最大620Oeの交換バイアス磁場を観測した事は超低消費電力動作の不揮発性磁気メモリ開発にとって大きな成果となった。