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arXiv · 1408.6780

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
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Abstract

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$_{10}$.

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J. Robert, F. Damay, K. Saito, A. M. Bataille, F. Porcher, G. André, A. Gukasov, J. -M. Mignot, H. Tanida, M. Sera. 2014-12-17. Detailed neutron diffraction study of magnetic order in NdFe$_2$Al$_{10}$. https://doi.org/10.1103/physrevb.90.224425

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