Spin frustration on layered antiferromagnetism revealed by spin-polarized STM

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K04881
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 29020:Thin film/surface and interfacial physical properties-related
• Research Institution: Osaka Kyoiku University
• Principal Investigator: Kawagoe Takeshi 大阪教育大学, 教育学部, 教授 (20346224)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 層状反強磁性薄膜 / スピン偏極走査型トンネル顕微鏡 / スピンフラストレーション / らせん転位

Outline of Final Research Achievements

In order to clarify spin frustration (SF) originating from screw dislocations, we investigate surface nanostructure and magnetism of layered anitiferromagnetic (AF) Cr(001) films by spin-polarized scanning tunneling microscope (SP-STM). High quality epitaxial Cr(001) films thinner than 3 nm, consisting of atomically flat terraces with distinct spin-polarized surface states, were successfully fabricated. In addition, distinct magnetic images featuring a layered AF order were clearly observed at RT even if the thickness was only 1.0 nm. By scrutinizing the topological and magnetic images obtained SP-STM, we found spin-frustrated triangular areas comprising a cluster of three screw dislocations and large SF area and an AF domain formation with a 90° quantum axis rotation induced by adjacent paired (4) screw dislocations. These novel types of screw dislocation-induced SF could not be observed in the previous studies and they were successfully reproduced by the micromagnetic simulation.

Free Research Field

表面磁性、表面・界面物性、スピントロニクス、磁性物理

Academic Significance and Societal Importance of the Research Achievements

反強磁性体を用いたスピントロニクスは、従来の強磁性体を用いたデバイスに比べ、漏れ磁場がない・応答時間が速い・磁場ノイズに強いなどの利点から近年注目されている。しかし、反強磁性体の磁気構造の検出は難しく、磁区形成に不明な点が多く、スピンフラストレーション(SF)も起きる。本研究で用いるスピン偏極STMは、反強磁性体の表面構造と磁気構造・SFの詳細を高精度で解明できる非常に適した方法である。本研究では層状反強磁性薄膜の欠陥によるSFと磁区形成メカニズムの詳細についての研究を行うが、これらの研究から反強磁性体を用いた近未来のスピンデバイスの材料開発の指針となる有益な情報が得られると期待される。