[10a-E208-1~11] 10.1 Emerging materials in spintronics and magnetics (including fabrication and characterization methodologies)

11:30 AM - 11:45 AM JST(2:30 AM - 2:45 AM UTC)Presentation by Applicant for JSAP Young Scientists Presentation AwardEnglish Presentation

[10a-E208-10] Novel Structural Insights into Interface-Driven Perpendicular Magnetic Anisotropy in MgO(111)/CoFeB Heterostructures

〇(DC)TARUNRAJU KAKINADA^1,2, Jieyuan Song¹, Jun Uzuhashi¹, Tadakatsu Ohkubo¹, Zhenchao Wen¹, Seiji Mitani^1,2, Hiroaki Sukegawa^1,2 (1.NIMS, 2.University of Tsukuba)

Keywords:

Perpendicular Magnetic Anisotropy (PMA),MgO/CoFeB,Perpendicular Magnetic Tunnel Junctions (p-MTJ)

Perpendicular magnetic anisotropy (PMA) at MgO/CoFeB interfaces is essential for p-MTJ-based MRAM devices. While MgO(001)/CoFeB systems have been extensively studied, the MgO(111)/CoFeB interface remains largely unexplored. In this study, we demonstrate room-temperature epitaxial growth of MgO(111) on Al₂O₃(0001) substrates by ultra-high-vacuum magnetron sputtering. CoFeB thickness-dependent magnetization measurements after post-annealing at 250°C yield an effective PMA energy density of 0.5 Merg/cm³, an interfacial anisotropy of 0.44 erg/cm², and an effective volume anisotropy of -0.60 Merg/cm³, confirming interface-driven PMA at the MgO(111)/CoFeB interface. Cross-sectional STEM and nano-beam electron diffraction reveal epitaxial fcc MgO(111) growth on the hcp Al₂O₃(0001) substrate with a sharp MgO/Al₂O₃ interface. In contrast, the MgO(111)/CoFeB interface is relatively rough and contains multidomain boundaries, which likely contributes to the reduced PMA energy compared with conventional MgO(001)/CoFeB interfaces. These findings suggest that further optimization of the MgO(111)/CoFeB interface is key toward (111)-oriented p-MTJs.