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通过实验和第一性原理研究了Ni50-xMn10+xGa30Cu10(x=0-10)系列Heusler合金的结构、马氏体相变和磁性.实验研究发现,当用Mn原子在化学上替换Ni原子,合金的晶格参数随成分线性增大,相应体系的马氏体相变温度线性降低;理论分析认为,体系合金的单胞尺寸和电子浓度的共同作用使马氏体相变温度随成分变化线性降低直至消失;体系中Mn对Ni原子的替换使交互作用较强的Ni(A,C)-Mn(B)原子对逐渐形成,这增强了磁性原子间总的交换耦合作用,实验观测到体系合金的居里温度随成分逐渐上升.基于KKR-CPA-LDA的第一性原理计算结果表明,在体系合金中Mn原子磁矩始终与Ni原子磁矩保持铁磁排列,且Mn原子为体系分子磁矩的主要贡献者,因此体系合金的分子磁矩随Mn原子数量线性增加,这与实验结果相一致.
The structure, martensitic transformation and magnetic properties of Ni50-xMn10 + xGa30Cu10 (x = 0-10) series Heusler alloys were investigated by means of experiments and first principles. The experimental results show that when Mn atoms are chemically replaced by Ni atoms, The lattice parameter of the alloy increases linearly with the composition, and the martensitic transformation temperature of the corresponding system decreases linearly. The theoretical analysis shows that the unit cell size and the electron concentration of the alloy increase the martensitic transformation temperature linearly with the composition Decrease until it disappears. The replacement of Ni atoms by Mn in the system gradually formed the strongly interacting pairs of Ni (A, C) -Mn (B) atoms, which enhances the total exchange coupling between the magnetic atoms. The experimental results show that the system The Curie temperature of the alloy gradually increases with the composition.First-principles calculations based on KKR-CPA-LDA show that the magnetic moment of Mn atom in the system alloy always keeps the ferromagnetic alignment with the Ni atomic moment, and the Mn atom is the system molecule Therefore, the molecular magnetic moment of the system alloy increases linearly with the number of Mn atoms, which is consistent with the experimental results.