Atomic scale characterizations of the exchange coupling in ferromagnetic/antiferromagnetic heterostructures by spin-polarized STM

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H05963
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Nanostructural physics
• Research Institution: The University of Tokyo
• Principal Investigator: MIYAMACHI Toshio 東京大学, 物性研究所, 助教 (10437361)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: スピン偏極STM / XAS/XMCD / 磁性超薄膜ヘテロ構造 / スピン再配列転移 / 表面・界面

Outline of Final Research Achievements

We performed spin-polarized STM and XAS/XMCD measurements for antiferromagnetic/ferromagnetic Mn/Fe thin film heterostructures grown on Cu(001). The purpose of this work was to elucidate microscopic origins of electronic and magnetic properties at the heterointerface. We observed the spin reorientation transition of the Fe layer in Mn/Fe thin film heterostructures from out-of-plane direction to in-plane direction with increasing the thickness of the Mn layer. Atomically-resolved STM observations in the process of the heterointerface formation revealed the structural transition from the disordered alloy to the ordered alloy at the heterointerface as the origin of the transition. Furthermore, with the help of atomic-scale observations of surface magnetic structures of the Mn layer by spin-polarized STM, we successfully demonstrated that the change in the easy magnetization direction of the Fe layer is originated from the magnetic coupling with the Mn layer at the heterointerface.

Free Research Field

ナノ磁性

Academic Significance and Societal Importance of the Research Achievements

本研究では、スピン偏極STMにXAS/XMCD測定を相補的に組み合わせた研究手法を用いて反強磁性/強磁性 Mn/Fe超薄膜ヘテロ構造の界面形成過程における磁気特性の逐次変化を原子スケールで明らかにした。さらに、界面磁気結合状態を決定する原子構造と電子状態の役割を個別に分離して理解することに成功した。本研究成果により磁性超薄膜ヘテロ構造の界面磁気特性を飛躍的に向上させ、磁気ヘッドに代表されるヘテロ接合デバイスのさらなる低消費電力化や高密度化につながることが期待できる。