Deterministic multi-level spin orbit torque switching using focused He+ ion beam irradiation

Abstract

He+ ion irradiation is used to pattern multiple areas of Pt/Co/W films with different irradiation doses in Hall bars. The resulting perpendicular magnetic anisotropy landscape enables selective multilevel current-induced switching with full deterministic control of the position and order of the individual switching elements. Key pattern design parameters are specified, opening a way to scalable multi-level switching devices.

Ion irradiation modulated magnetic properties of materials and its applications

“…在人工神经网络中， 具有记忆和学习功能的人工突触器件是神经形态系统的 重要组成部分。人工突触需要具有非易失性和电阻或电导信号连续可变的性能。 而磁矩多态翻转器件也具有上述特点， 其翻转行为可以用来模拟大脑中神经突触 的权重变化。X.Zhao [92] 等人使用 15 keV He + 辐照了具有 W/CoFeB/MgO 结构的 霍尔十字器件受辐照的区域垂直磁各向异性降低，该区域将快速成核并扩张，同 时，由于磁畴壁在辐照与非辐照区边界运动时会受到强钉扎作，霍尔十字处的磁 矩存在多级翻转。因此，只需改变辐照区与非辐照区面积比例，即可诱导出一系 列的中间反常霍尔电阻， 如图 8a-8d 所示。 J.Kurian [93] 等人则利用 He + 以 13、 20、 磁矩翻转过程及其模拟的翻转回线 [92] ；(e-g)在 125 mT 面内辅助场下，SOT 驱动辐照样品的多级 翻转反常霍尔与磁光克尔图像 [93] 。 Figure 8. Two polymorphic flipping devices.…”

“…Two polymorphic flipping devices. (a-d) the SOT-driven magnetic moment flipping process of Hall Cross with different linewidths under the magnetic field in the μ 0 H x = 50 mT [92] ; (e-g) under the auxiliary field of 125 mT, the SOT-driven multistage switching anomalous Hall loop and the magneto-optical Kerr image of irradiated sample [93] .…”