講演情報
[8a-E207-11]Nonlinear Hall effect in a Mn- and Ta-co-doped RuO2 epitaxial thin film
〇(M2)Haruto Ohboshi1, Hiroshi Naganuma2, Kenta Amemiya3, Shintaro Yasui4, Takaki Nomura1, Masaaki Tanaka1,5, Shinobu Ohya1,5 (1.EEIS, The Univ. of Tokyo, 2.Univ. of Toyama, 3.IMSS, KEK, 4.ZC, Science Tokyo, 5.CSRN, The Univ. of Tokyo)
キーワード：
RuO2、altermagnet、anomalous hall effect
RuO2 is an altermagnetic candidate with a predicted spin-split band structure, but its long-range magnetic order remains controversial. Theory suggests carrier doping stabilizes its magnetic phase. To study this, we grew four types of epitaxial thin films on TiO2 (110) substrates by molecular beam epitaxy: undoped RuO2, Mn-doped (Ru0.98Mn0.02O2), Ta-doped (Ru0.99Ta0.01O2), and Mn/Ta-co-doped (Ru0.97Mn0.02Ta0.01O2). At 1.8 K, a distinct nonlinear Hall resistivity was observed exclusively in the co-doped film, showing that the coexistence of Mn and Ta is crucial for this anomalous transport. Furthermore, X-ray magnetic linear dichroism (XMLD) at the Ru edge was observed in the co-doped film at room temperature, suggesting electronic or magnetic anisotropy. However, XMLD alone does not prove long-range altermagnetic order due to possible structural distortions. Mechanisms for the nonlinear Hall effect may include altermagnetic Berry curvature, multi-carrier transport, or extrinsic scattering from Mn moments and Ta spin-orbit coupling.