Abstract Polycrystalline NiCrGa half Heusler alloy, which is predicted to be a half-metallic ferromagnet from first principles calculations, has been synthesized by arc meting technique and its structural, magnetic as well as the electronic properties have been studied. The measured x-ray diffraction (XRD) pattern shows the signature of a disordered structure. Magnetization and magnetoresistance measurements indicate a competition between ferromagnetic and antiferromagnetic correlations in the sample, with no evidence of long range magnetic order down to the lowest temperature (2 K) and highest magnetic field (70 kOe) studied. The experimentally observed structural and magnetic properties are found to be significantly different from the theoretically predicted properties of the ordered cubic C1b structure. To probe into the possibility of the presence of atomic disorder in the system, we have performed theoretical calculations using the spin-polarized-relativistic Korringa-Kohn-Rostoker method (SPR-KKR). By comparing the experimental data from XRD, magnetization, photoelectron spectroscopy measurements and theoretical calculations, we conclude that NiCrGa has significant amount of atomic disorder. Although, the ordered structure is energetically more stable than the disordered structures, we find that after synthesis, the system tends to stabilize in a disordered structure. The nature of the disorder has been ascertained from experiments and the corresponding electronic structure and magnetic properties have been obtained. With this atomic disorder present in the sample, the ferromagnetic ordering is disturbed and the spin polarization is consequently reduced.

中文翻译：

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原子无序的存在及其对 NiCrGa 半赫斯勒合金磁电性能的影响

摘要 用电弧测量技术合成了多晶NiCrGa半赫斯勒合金，从第一性原理计算预测为半金属铁磁体，并对其结构、磁性和电子特性进行了研究。测量的 X 射线衍射 (XRD) 图案显示出无序结构的特征。磁化和磁阻测量表明样品中铁磁和反铁磁相关性之间存在竞争，没有证据表明研究到最低温度 (2 K) 和最高磁场 (70 kOe) 的长程磁序。发现实验观察到的结构和磁性性质与有序立方 C1b 结构的理论预测性质显着不同。为了探究系统中存在原子无序的可能性，我们使用自旋极化相对论 Korringa-Kohn-Rostoker 方法 (SPR-KKR) 进行了理论计算。通过比较来自 XRD、磁化强度、光电子能谱测量和理论计算的实验数据，我们得出结论，NiCrGa 具有大量的原子无序。虽然有序结构比无序结构在能量上更稳定，但我们发现合成后，系统趋于稳定在无序结构中。已经通过实验确定了无序的性质，并获得了相应的电子结构和磁性。由于样品中存在这种原子无序，