Tunneling Spin Valves Based on Fe3GeTe2/hBN/Fe3GeTe2 van der Waals Heterostructures
Tunneling Spin Valves Based on Fe3GeTe2/hBN/Fe3GeTe2 van der Waals Heterostructures
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DOI：
10.1021/acs.nanolett.8b01278
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发表时间：
2018-07-01
期刊：
影响因子：
10.8
通讯作者：
Morpurgo, Alberto F.
中科院分区：
文献类型：
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作者：
Wang, Zhe;Sapkota, Deepak;Morpurgo, Alberto F.
薄的货车瓦（vdW）层状磁性材料为实现具有新功能的vdW异质结构提供了可能。在这里，我们报告的实现和调查隧道自旋阀的基础上组成的原子级薄的hBN层作为隧道势垒和两个剥离的Fe 3GeTe 2晶体作为铁磁电极的货车德瓦尔斯异质结构。低温反常霍尔效应测量表明，薄Fe 3GeTe 2晶体是金属铁磁体，具有垂直于层的易磁化轴，并且在磁场值下具有非常尖锐的磁化切换，该磁场值略微取决于它们的几何形状。在Fe 3GeTe 2/hBN/Fe 3GeTe 2异质结构中，我们观察到隧穿电阻的教科书行为，当两个电极中的磁化相互平行（反平行）时，隧穿电阻最小（最大）。在低温下的磁电阻是160%，由此我们确定Fe 3GeTe 2的自旋极化为0.66，对应于83%和17%的多数和少数载流子，分别。测量结果还表明，随着温度的升高，从隧道磁电阻提取的自旋极化的演变是成比例的温度依赖性的磁化强度提取的异常霍尔电导率的分析。这表明，表面的磁性能是代表那些散装，可以预期的VDW材料。
Thin van der Waals (vdW) layered magnetic materials hold the possibility of realizing vdW heterostructures with new functionalities. Here, we report on the realization and investigation of tunneling spin valves based on van der Waals heterostructures consisting of an atomically thin hBN layer acting as tunnel barrier and two exfoliated Fe3GeTe2 crystals acting as ferromagnetic electrodes. Low-temperature anomalous Hall effect measurements show that thin Fe3GeTe2 crystals are metallic ferromagnets with an easy axis perpendicular to the layers and a very sharp magnetization switching at magnetic field values that depends slightly on their geometry. In Fe3GeTe2/hBN/Fe3GeTe2 heterostructures, we observe textbook behavior of the tunneling resistance, which is minimum (maximum) when the magnetization in the two electrodes is parallel (antiparallel) to each other. The magnetoresistance is 160% at low temperature, from which we determine the spin polarization of Fe3GeTe2 to be 0.66, corresponding to 83% and 17% of the majority and minority carriers, respectively. The measurements also show that, with increasing temperature, the evolution of the spin polarization extracted from the tunneling magnetoresistance is proportional to the temperature dependence of the magnetization extracted from the analysis of the anomalous Hall conductivity. This suggests that the magnetic properties of the surface are representative of those of the bulk, as may be expected for vdW materials.