四元Heusler合金NiMnFeGa中Fe原子的磁性贡献

The contribution of Fe atom to the magnetic moment of quaternary Heusler alloy NiMnFeGa

用熔炼和甩带的方法制备了组分为Ni50 FexMn2 5-xGa2 5(x =0— 2 5 )的系列样品 .x射线衍射实验结果表明 ,当Fe取代Mn的含量x <17时 ,用熔炼和甩带的方法均能合成高度有序的L2 1 结构的Heusler相 .而当x >17时 ,普通熔炼方法只能得到低有序度的γ相 ,只有采用甩带急冷的方法才能获得高度有序的纯L2 1 结构的化合物 .根据交流磁化率和分子磁矩的测试结果 ,初步分析了Fe原子对化合物磁性的贡献 ,认为Fe原子占据了Mn原子的位置后 ,具有高于一般含铁合金的原子磁矩 ,可达 2 5 5— 3 5 5 μB.

We have synthesized the pseudo-quaternary Heusler alloy Ni50Mn25-xFexGa25 (x = 0-25) by arc-melting and melt-spinning techniques. The structure, magnetic properties, and martensitic phase transformation were investigated. The thermoelastic martensitic transformation characteristics and x-ray diffraction confirmed the high chemical ordering L2(1) structure of our samples in the whole doping range. The dopant of iron decreases the martensitic transformation temperature and increase the Curie temperature for the doping level of x < 17. The ferromagnetic contribution of Fe atoms in Ni50.5Mn25-xFexGa24.5 has been investigated in detail by precisely measuring the magnetization at 4K. It has been found that Fe atoms were indeed in Mn positions and contributed a localized moment up to 2.55-3.55 mu(B).