Yu Litao, Li Zhe, Zhu Jiajun, Liu Hongwei, Zhang Yuanlei, Cao Yiming, Xu Kun, Liu Yongsheng
Department of Physics, Shanghai University of Electric Power, Shanghai 200090, China.
Center for Magnetic Materials and Devices, College of Physics and Electronic Engineering, Qujing Normal University, Qujing 655011, China.
Materials (Basel). 2022 Sep 4;15(17):6138. doi: 10.3390/ma15176138.
This study performed a systematic experimental investigation into the structural, magnetic, and transport properties of the CoVGa Heusler alloy, which was theoretically predicted to exhibit half-metallic ferromagnetism. It has been experimentally found that the studied alloy has a relatively high-ordered 2 cubic structure at room temperature and orders ferromagnetically below 350 K. Interestingly, by fitting the electric transport data with the properly governing equations in two different temperature regions, the two-magnon scattering process (the T9/2 dependence) appears in the temperature range from 30 to 75 K. Moreover, the magnetoresistance effect changes from a negative value to a positive value when the temperature is below 100 K. Such experimental findings provide indirect evidence that the half-metallic nature of this alloy is retained only when the temperature is below 100 K. On the other hand, the magnetic transport measurements indicate that the anomalous Hall coefficient of this alloy increases when the temperature increases and reaches a relatively high value (8.3 μΩ·cm/T) at 300 K due to its lower saturated magnetization. By analyzing the anomalous Hall resistivity scale with the longitudinal resistivity, it was also found that the anomalous Hall effect can be ascribed to the combined effect of extrinsic skew scattering and intrinsic Berry curvature, but the latter contribution plays a dominant role.
本研究对CoVGa赫斯勒合金的结构、磁性和输运性质进行了系统的实验研究，该合金在理论上被预测具有半金属铁磁性。实验发现，所研究的合金在室温下具有相对高阶的立方结构，并在约350 K以下呈现铁磁有序。有趣的是，通过在两个不同温度区域用适当的控制方程拟合电输运数据，在30至75 K的温度范围内出现了双磁振子散射过程（T9/2依赖性）。此外，当温度低于100 K时，磁电阻效应从负值变为正值。这些实验结果提供了间接证据，表明该合金仅在温度低于100 K时才保留半金属性质。另一方面，磁输运测量表明，该合金的反常霍尔系数随温度升高而增加，由于其较低的饱和磁化强度，在300 K时达到相对较高的值（约8.3 μΩ·cm/T）。通过分析反常霍尔电阻率与纵向电阻率的标度关系，还发现反常霍尔效应可归因于外在的斜散射和内在的贝里曲率的综合作用，但后者的贡献起主导作用。
