Study of light-induced magnetic reversal of thin films by time-resolved x-ray magnetic circular dichroism measurement

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K14334
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Condensed matter physics II
• Research Institution: The University of Tokyo
• Principal Investigator: HIRATA Yasuyuki 東京大学, 物性研究所, 助教 (50750692)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 薄膜磁性 / 磁化反転 / 光誘起相転移 / X線自由電子レーザー / X線磁気円二色性 / X線磁気光学カー効果 / ポンプ・プローブ法

Outline of Final Research Achievements

We have clarified the magnetic dynamics of ferromagnetic perpendicularly-magnetized thin films by time-resolved resonant magneto-optical measurement using an x-ray free electron laser, and explored the origin of all-optical helicity-dependent switching (AO-HDS) where the magnetism can be controlled by light irradiation. Our results of the time-resolved x-ray magnetic circular dichroism of L10-FePt thin film and the time-resolved magneto-optical Kerr effect of Co-Pt superlattice thin film have shown that the time scale of demagnetization of Pt site is more than 6 times longer than that of Fe and Co sites. It was suggested that the site dependence of magnetic dynamics can be essential for the mechanism of AO-HDS.

Free Research Field

光物性

Academic Significance and Societal Importance of the Research Achievements

近年では電子計算機の処理速度の高速化に伴い、記憶媒体の応答も高速であることが要求されるようになりつつある。本研究で得られた薄膜磁性の光照射に対する応答についての知見は、基礎的な物質科学への貢献にとどまらず、光を利用した高速かつ効率的な磁化の制御が可能となる条件の解明を通し、優れた磁気記憶媒体の開発や今後のスピントロニクスの発展にもつながると期待される。