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arXiv 1408.6780cond-mat.str-el
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NdFe $_2$ Al $_{10}$磁序的中子衍射研究

Detailed neutron diffraction study of magnetic order in NdFe$_2$Al$_{10}$

J. Robert, F. Damay, K. Saito, A. M. Bataille, F. Porcher, G. André, A. Gukasov, J. -M. Mignot, H. Tanida, M. Sera

摘要:

用粉末和单晶中子衍射研究了正交晶系化合物NdFePDMATHABMMAlPDMATHABMN。在$T_N$ = 3.9K以下,Nd-$^{3+}$磁矩有序排列为双$k$ [ $\mathbf{k}_1 = (0, \frac{3}{4}, 0)$,$\mathbf{k}_2 = (0, \frac{1}{4}, 0)$ ]共线磁结构,其晶胞由四个沿$b$方向的正交晶系单元组成,精细计算表明,该结构由沿$b$方向堆叠的(010)铁磁平面组成,其中力矩平行于$a$(根据体磁化测量的易各向异性轴)取向并且在幅度上几乎相等($\approx 1.7-1.9\ μ_B$)。交替的8-平面序列提供最好的协议的数据原来是产生最低的交换能量,如果一个人假设反铁磁近邻交换相互作用与$J_1 \gg J_2, J_3$。随着温度的升高,单晶测量表明在$T = 2.7$ K时$\mathbf{k}_2$组分受到抑制,支持了先前在2- 2.5 K附近观察到的反常现象是由平方跃迁引起的观点。在沿$a$轴施加的磁场中,磁性布拉格卫星在$H_c = 2.45$ T处消失,与早期的测量结果一致。比较了Ce $T_2$ Al $_{10}$($T$:Ru,Os)和TbFe $_2$ Al $_{10}$中出现的相关磁序。

英文摘要:

The orthorhombic compound NdFe$_2$Al$_{10}$ has been studied by powder and single-crystal neutron diffraction. Below $T_N$ = 3.9 K, the Nd$^{3+}$ magnetic moments order in a double-$k$ [$\mathbf{k}_1 = (0, \frac{3}{4}, 0)$, $\mathbf{k}_2 = (0, \frac{1}{4}, 0)$] collinear magnetic structure, whose unit cell consists of four orthorhombic units in the $b$ direction.The refinements show that this structure consists of (0 1 0) ferromagnetic planes stacked along $b$, in which the moments are oriented parallel to $a$ (the easy anisotropy axis according to bulk magnetization measurements) and nearly equal in magnitude ($\approx 1.7-1.9\ μ_B$). The alternating 8-plane sequence providing the best agreement to the data turns out to be that which yields the lowest exchange energy if one assumes antiferromagnetic near-neighbor exchange interactions with $J_1 \gg J_2, J_3$. With increasing temperature, the single-crystal measurements indicate the suppression of the $\mathbf{k}_2$ component at $T = 2.7$ K, supporting the idea that the anomalies previously observed around 2--2.5 K result from a squaring transition. In a magnetic field applied along the $a$ axis, the magnetic Bragg satellites disappear at $H_c = 2.45$ T, in agreement with earlier measurements. Comparisons are made with related magnetic orders occurring in Ce$T_2$Al$_{10}$ ($T$: Ru, Os) and TbFe$_2$Al$_{10}$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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