[15p-PB1-1~57] 10 スピントロニクス・マグネティクス（ポスター）

[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.