基于高垂直磁各向异性L10 FePt单层膜的电流驱动SOT磁化翻转研究

工程（英文） ›› 2022, Vol. 12 ›› Issue (5) : 55 -61. DOI: 10.1016/j.eng.2021.09.018

董凯锋 ^a^,^b ,
孙超 ^a^,^b ,
朱来哲 ^a^,^b ,
焦义义 ^a^,^b ,
陶应 ^a^,^b ,
胡欣 ^a^,^b ,
李若凡 ^c ,
张帅 ^c ,
郭喆 ^c ,
罗世江 ^c ,
杨晓非 ^c ,
李少平 ^d ,
游龙 ^c^,^e^,^f

作者信息 +

Current-Induced Magnetic Switching in an L10 FePt Single Layer with Large Perpendicular Anisotropy through Spin–Orbit Torque

Kaifeng Dong ^a^,^b ,
Chao Sun ^a^,^b ,
Laizhe Zhu ^a^,^b ,
Yiyi Jiao ^a^,^b ,
Ying Tao ^a^,^b ,
Xin Hu ^a^,^b ,
Ruofan Li ^c ,
Shuai Zhang ^c ,
Zhe Guo ^c ,
Shijiang Luo ^c ,
Xiaofei Yang ^c ,
Shaoping Li ^d ,
Long You ^c^,^e^,^f

Author information +

文章历史 +

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摘要

本研究利用自旋轨道力矩（SOT）在单层L1₀ FePt 铁磁层中实现了电流驱动的部分磁化翻转，其中L1₀FePt 具有高垂直各向异性，K_u⊥为1.19 × 10⁷erg‧cm⁻³ （1 erg‧cm⁻³ = 0.1 J‧m⁻³）。与传统Ta/CoFeB/MgO 结构相比，L1₀ FePt 的SOT效率（β_DL）要高几倍，可达8 × 10⁻⁶Oe∙(A‧cm⁻²)⁻¹（ 1 Oe = 79.57747 A‧m⁻¹）。L1₀ FePt的SOT效应起源于FePt 内部分布不均匀的位错和缺陷造成的结构反演对称性破缺。进一步，采用MgO和SrTiO₃ （STO）两种衬底制备FePt 自旋器件，基于MgO衬底的FePt 具有颗粒状结构，而生长于STO衬底上的FePt 则为连续结构。研究发现，基于MgO衬底的FePt 器件具备更高的SOT等效场及SOT效率，且FePt 的SOT效率不仅取决于溅射温度导致的化学有序度变化，还与晶格失配导致的微观结构变化有关。本文的研究可为基于SOT效应的高热稳定性电致磁记录提供有效的方法。

Abstract

In this study, current-induced partial magnetization-based switching was realized through the spin–orbit torque (SOT) in single-layer L1₀ FePt with a perpendicular anisotropy (Ku⊥) of 1.19 × 107 erg‧cm⁻³ (1 erg‧cm⁻³ = 0.1 J‧m^₋₃), and its corresponding SOT efficiency (βDL) was 8 × 10⁻⁶ Oe∙(A‧cm⁻²)⁻¹ (1 Oe = 79.57747 A‧m⁻¹), which is several times higher than that of the traditional Ta/CoFeB/MgO structure reported in past work. The SOT in the FePt films originated from the structural inversion asymmetry in the FePt films since the dislocations and defects were inhomogeneously distributed within the samples. Furthermore, the FePt grown on MgO with a granular structure had a larger effective SOT field and efficiency than that grown on SrTiO₃ (STO) with a continuous structure. The SOT efficiency was found to be considerably dependent on not only the sputtering temperature-induced chemical ordering but also the lattice mismatch-induced evolution of the microstructure. Our findings can provide a useful means of efficiently electrically controlling a magnetic bit that is highly thermally stable via SOT.