Time-resolved SP-STM study of spin dynamics in ferromagnetic nanostructures

2019 Fiscal Year Final Research Report

• Project/Area Number: 17H02779
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Thin film/Surface and interfacial physical properties
• Research Institution: Tohoku University
• Principal Investigator: Oka Hirofumi 東北大学, 材料科学高等研究所, 助教 (70374600)
• Co-Investigator(Kenkyū-buntansha): 米田 忠弘 東北大学, 多元物質科学研究所, 教授 (30312234)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 強磁性ナノ構造 / スピン偏極STM / スピン緩和時間 / 時間分解測定

Outline of Final Research Achievements

In order to investigate spin relaxation processes in ferromagnetic nanostructures, we established nanostructures with simple spin-dependent electronic states and spin-polarized scanning tunneling microscopy (STM) with temporal resolution.
Co nanostructures with triangular shape were formed on Cu(111) substrate, followed by sequential deposition of Fe, Ni, or Ag. This procedure resulted in the formation of a core-shell type of nanostructures that Co was surrounded by other materials. Spin-polarized STM measurements revealed that Co nanostructures exhibited two free-electron like spin-polarized surface states. Analyses on the energy width of discrete free-electron like states implied that the spin relaxation time was longer for core-shell type nanostructures than for pure Co nanostructures.

Free Research Field

表面電子物性

Academic Significance and Societal Importance of the Research Achievements

強磁性ナノ構造における電子スピンの緩和過程を明らかにすることは、電子のスピン状態の保持・伝達につながり、スピン状態の制御を可能にするため、新規スピントロニクスデバイスの創出に向けて重要な課題である。単純なスピン偏極電子状態を示す強磁性Coナノ構造はその測定対象のモデルケースとなり得、他の材料で囲むことによりスピン間時間を変調できる可能性を示した。今後、時間分解測定のナノ構造内での局所測定につなげていく。