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

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 ($\approx 1.7-1.9{\mu }_B$). 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${}_{10}$.

9 pages, 10 figures. Accepted for publication in Phys. Rev. B

References in corpus (2)

• Long-range order and low-energy magnetic excitations in CeRu2Al10
• Anisotropic spin-dynamics in the Kondo semiconductor CeRu2Al10

Cited by in corpus (1)

• Temperature-Dependent Cycloidal Magnetic Structure in GdRu${}_2$Al${}_{10}$ Studied by Resonant X-ray Diffraction