Highly Efficient Spin-Orbit Torque and Switching of Layered Ferromagnet Fe3GeTe2
Highly Efficient Spin-Orbit Torque and Switching of Layered Ferromagnet Fe3GeTe2
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DOI：
10.1021/acs.nanolett.9b01043
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发表时间：
2019-07-01
期刊：
影响因子：
10.8
通讯作者：
Shi, Jing
中科院分区：
文献类型：
--
作者：
Alghamdi, Mohammed;Lohmann, Mark;Shi, Jing
在范德华(VDW)层状铁磁体中，Fe3GeTe2(FGT)是形成FGT/重金属异质结的理想候选材料，可用于研究自旋轨道力矩(SOT)效应。它的金属性、建立在单原子层中的强垂直磁各向异性、相对较高的居里温度(T-c类似于225K)以及静电栅极的可调性为实现单层全VDW纳米器件的最终高SOT极限提供了诱人的可能性。在这项研究中，我们用5 nm的铂溅射到类似于1523 nm剥离的FGT薄片的原子平面上，制备了FGT/铂异质结。在铂中产生的自旋电流对FGT的磁化作用类似于阻尼型SOT。在与2.5×10(11)A/m(2)电流密度相近的电流密度下，SOT引起FGT磁化强度的开关，这是由FGT的反常霍尔效应检测到的。为了量化SOT效应，我们测量了外加磁场旋转平面内FGT磁化强度时的二次谐霍尔响应。我们的分析表明，SOT效率与含有3D铁磁金属的最佳异质结相当，而比含有3D亚铁磁性绝缘体的最佳异质结要大得多。如此高的效率归功于原子平坦的FGT/Pt界面，这表明利用VDW异质结构来制作高效自旋电子学纳米器件具有巨大的潜力。
Among van der Waals (vdW) layered ferromagnets, Fe3GeTe2 (FGT) is an excellent candidate material to form FGT/heavy metal heterostructures for studying the effect of spinorbit torques (SOT). Its metallicity, strong perpendicular magnetic anisotropy built in the single atomic layers, relatively high Curie temperature (T-c similar to 225 K), and electrostatic gate tunability offer a tantalizing possibility of achieving the ultimate high SOT limit in monolayer all-vdW nanodevices. In this study, we fabricate heterostructures of FGT/Pt with 5 nm of Pt sputtered onto the atomically flat surface of similar to 1523 nm exfoliated FGT flakes. The spin current generated in Pt exerts a damping-like SOT on FGT magnetization. At similar to 2.5 x 10(11) A/m(2) current density, SOT causes the FGT magnetization to switch, which is detected by the anomalous Hall effect of FGT. To quantify the SOT effect, we measure the second harmonic Hall responses as the applied magnetic field rotates the FGT magnetization in the plane. Our analysis shows that the SOT efficiency is comparable with that of the best heterostructures containing three-dimensional (3D) ferromagnetic metals and much larger than that of heterostructures containing 3D ferrimagnetic insulators. Such large efficiency is attributed to the atomically flat FGT/Pt interface, which demonstrates the great potential of exploiting vdW heterostructures for highly efficient spintronic nanodevices.