Presentation Information
[16a-S4_201-2]Control of the Skyrmion Hall Angle by Introducing Ultrathin Interfacial Layers
in Ta/CoFeB/MgO
〇(M2)Kohei Yamashita1, Tang Yujian1, Tsz Chung Cheng1, Yuichiro Kurokawa1, Hiromi Yuasa1 (1.Kyushu Univ.)
Keywords:
spintronics,skyrmion
Magnetic skyrmions are topologically protected spin textures that are promising for next-generation spintronic devices because of their high-speed motion, high data density, and low power consumption [1]. However, current-driven skyrmions exhibit the skyrmion Hall effect, causing transverse motion due to their nonzero topological charge [2]. The skyrmion Hall angle can be tuned by controlling the Dzyaloshinskii–Moriya interaction (DMI) [3]. Here, we control the skyrmion Hall angle by tuning the interfacial DMI via ultrathin W or Pt insertion at the Ta/CoFeB interface in a Ta/CoFeB/MgO stack with perpendicular magnetic anisotropy.
Ta (5 nm)/Pt or W (0 or 0.2 nm)/CoFeB (1 nm)/MgO (1 nm)/Ta (3 nm) multilayers were deposited by magnetron sputtering and annealed to optimize perpendicular magnetic anisotropy [4]. Nanowires and Hall-bar devices were fabricated for skyrmion observation and spin–orbit torque (SOT) measurements, and magnetic textures were observed by polar MOKE microscopy.
Figure 1 shows representative MOKE images of skyrmions. The skyrmion Hall angle is 50° in the sample without an insertion layer and is modified to 66° and 41° by ultrathin Pt and W insertion, respectively. These changes are attributed to DMI variation. The DMI constants estimated from SOT measurements [5] are 0.21, 0.18, and 0.27 mJ/m² for the no-insertion, Pt-inserted, and W-inserted samples, respectively. Figure 2 summarizes the relationship between the DMI constant and , revealing a clear negative correlation. These results demonstrate that the skyrmion Hall angle can be effectively controlled by ultrathin interfacial layer insertion.
[1] W. Kang, et al., IEEE 104, 2040 (2016). [2] G. Chen, Nature Phys. 13 112 (2017).
[3] Bingqian Dai et al., Sci. Adv. 9, 6836 (2023). [4] M. Goto, et al., AIP Advances 13, 025216 (2023).
[5] C.-F. Pai et al., Phys. Rev. B 93, 144409 (2016).
Ta (5 nm)/Pt or W (0 or 0.2 nm)/CoFeB (1 nm)/MgO (1 nm)/Ta (3 nm) multilayers were deposited by magnetron sputtering and annealed to optimize perpendicular magnetic anisotropy [4]. Nanowires and Hall-bar devices were fabricated for skyrmion observation and spin–orbit torque (SOT) measurements, and magnetic textures were observed by polar MOKE microscopy.
Figure 1 shows representative MOKE images of skyrmions. The skyrmion Hall angle is 50° in the sample without an insertion layer and is modified to 66° and 41° by ultrathin Pt and W insertion, respectively. These changes are attributed to DMI variation. The DMI constants estimated from SOT measurements [5] are 0.21, 0.18, and 0.27 mJ/m² for the no-insertion, Pt-inserted, and W-inserted samples, respectively. Figure 2 summarizes the relationship between the DMI constant and , revealing a clear negative correlation. These results demonstrate that the skyrmion Hall angle can be effectively controlled by ultrathin interfacial layer insertion.
[1] W. Kang, et al., IEEE 104, 2040 (2016). [2] G. Chen, Nature Phys. 13 112 (2017).
[3] Bingqian Dai et al., Sci. Adv. 9, 6836 (2023). [4] M. Goto, et al., AIP Advances 13, 025216 (2023).
[5] C.-F. Pai et al., Phys. Rev. B 93, 144409 (2016).