講演情報
[15p-PB1-32]c-Al2O3(0001)基板上のRuO2エピタキシャル膜のトリプルドメイン構造
佐藤 幸生1、Nguyen Anh2、大坪 嘉之3、上野 哲郎7、黒田 文彬4、福島 鉄也4、大星 温音5、大矢 忍5、〇永沼 博6 (1.熊本大、2.東北大CSIS、3.QSTナノテラス、4.産総研、5.東大、6.名古屋大、7.QST)
キーワード：
RuO2、トリプルドメイン、走査透過型電子顕微鏡
Ruthenium dioxide (RuO2) is a prototypical altermagnetic material that exhibits long-range antiferromagnetic order together with momentum-dependent spin splitting, while maintaining zero net magnetization. Owing to these properties, RuO2 is regarded as a promising platform for antiferromagnetic spintronics, especially in high-quality epitaxial thin films. RuO2 thin films with a thickness of 50 nm were grown on c-Al2O3 (0001) substrates by reactive sputtering. Although a triple-domain epitaxial structure has been theoretically expected due to the threefold symmetry of the sapphire substrate, direct experimental evidence has been lacking. In this work, plane-view scanning transmission electron microscopy combined with inverse fast Fourier transform analysis enabled the first direct visualization of the triple-domain structure, clearly resolving three rotational domains and their spatial distribution. The antiferromagnetic properties were further investigated by X-ray magnetic linear dichroism measurements at the Ru M3,2 edge (KEK, PF BL16) and the Ru L3,2 edge (Nanoterasu, BL13U). No XMLD signal was detected under normal-incidence geometry, which is attributed to the cancellation of Néel vectors caused by the X-ray beam size being larger than the individual domain size. First-principles calculations incorporating spin-polarized core-level transitions successfully reproduced key features of the XMLD spectra. These results highlight the critical role of epitaxial domain structures in determining the magnetic response of altermagnetic RuO2 films.