Advanced Magnetic Materials Laboratory, Department of Physics, Indian Institute of Technology (Madras), Chennai 60036, India.
J Phys Condens Matter. 2012 Aug 22;24(33):336007. doi: 10.1088/0953-8984/24/33/336007. Epub 2012 Jul 27.
The band structure calculation for the compound Mn(2)VGa carried out using the plane wave self-consistent field package with generalized gradient approximation shows that the compound is nearly half-metallic at the equilibrium lattice parameter. However, theoretical investigations have shown that a certain percentage of atomic anti-site disorder can destroy the half-metallic nature of the sample. Hence it is important to quantify the site disorder in these systems. We have deduced the percentage of atomic anti-site disorder from the refinement of the higher angle room temperature (300 K) neutron diffraction (ND) pattern and it was observed to be roughly 8% in our sample. The field variation of resistance recorded at different temperatures shows a positive slope at low temperatures and a negative slope at higher temperatures, indicating the half-metallic character at low temperatures. The ab initio calculations predict a ferrimagnetic ground state for this system. The analysis of the magnetic structure from ND data measured at 6 K yields magnetic moment values of 1.28 μ(B) and -0.7 μ(B) for Mn and V, respectively, confirming the ferrimagnetic ordering.
使用基于广义梯度近似的平面波自洽场方法对化合物 Mn(2)VGa 的能带结构进行了计算，结果表明，在平衡晶格参数下，该化合物几乎是半金属的。然而，理论研究表明，一定比例的原子反位无序可以破坏样品的半金属性质。因此，定量研究这些体系中的位错是很重要的。我们从高温（300 K）中子衍射（ND）图谱的精修中推导出了原子反位无序的百分比，在我们的样品中大约为 8%。在不同温度下记录的电阻随磁场的变化显示，在低温下斜率为正，在高温下斜率为负，表明在低温下具有半金属性质。从头算计算预测该体系具有亚铁磁基态。从在 6 K 下测量的 ND 数据得到的磁结构分析得出 Mn 和 V 的磁矩值分别为 1.28 μ(B)和-0.7 μ(B)，证实了亚铁磁有序。
