NiFe/Pt双层薄膜中的自旋霍尔磁阻

Investigation on Spin Hall Magnetoresistance of NiFe/Pt Bilayer Films

【目的】研究NiFe/Pt双层薄膜中的自旋霍尔磁阻(SMR),其中NiFe是铁磁金属导体。【方法】用标准四探针法测量不同Pt层厚度的NiFe/Pt电阻,通过拟合得到Pt层和NiFe层的电阻率;测量NiFe/Pt薄膜纵向磁电阻的磁场依赖特性。【结果】Pt层电阻率远小于NiFe层电阻率,表明电流几乎仅在Pt层流通。此外,界面处的自旋混合电导及纵向电阻Rxx的磁场角度依赖特性进一步表明Rxx由SMR主导,没有各向异磁阻(AMR)的贡献。分别在x,y和z轴施加磁场均观测到SMR,但是SMR的磁阻率不同,最大约为0.1%。不同磁场下SMR的角度依赖特性表明SMR可由小磁场控制。【结论】基于SMR的新型磁阻传感器可用于海洋科学技术中磁场信息探测。

【Objective】The spin Hall magentoresistance (SMR) was studied in NiFe/Pt bilayers, where NiFe is a ferromagnetic metal.【Methods】The Pt thickness dependence of resistance of NiFe/Pt was measured by the standard four-point Hall probing system, and the resistivity of Pt and NiFe layers was obtained with the fitting. Subsequently, the magnetic field dependent longitudinal magentoresistance of NiFe/Pt bilayer was measured.【Results】The resistivity of Pt layer was much smaller than that of the NiFe layer, which indicates that all the current only follows in Pt layer. In addition, both the spin-mixing conductance at the interface and angular dependence of the longitudinal resistance Rxx further indicate that Rxx is dominated by SMR without the contribution of anisotropic magnetoresistance. SMR can be observed under the external field applied in x, y and z axes, respectively. However, the magnetoresistance ratio is different among them, and the maximum difference is about 0.1%. The angular dependent SMR in the NiFe/Pt bilayer under various magnetic fields indicates that SMR can be controlled by a small magnetic field.【Conclusion】The results of this study indicates that the SMR-based magentoresistive sensor could be used for the detection of magnetic fields in marine science and technology.