The crystal and magnetic structures in R₂Ni_1.78In (R = Ho, Er and Tm) have been studied by neutron diffraction. The compounds crystallize in a tetragonal crystal structure of the Mo₂FeB₂ type (space group P4/mbm). At low temperatures, the magnetic moments, localized solely on the rare earth atoms, form antiferromagnetic structures described by the propagation vector k = [k_x, k_x, ½], with k_x equal to ¼ for R = Er and Tm or 0.3074 (4) for R = Ho. The magnetic moments are parallel to the c axis for R = Ho or lie within the (001) plane for R = Er and Tm. The obtained magnetic structures are discussed on the basis of symmetry analysis. The rare earth magnetic moments, determined from neutron diffraction data collected at 1.6 K, are 6.5 (1) μ_B (Er) and 6.09 (4) μ_B (Tm), while in the incommensurate modulated magnetic structure in Ho₂Ni_1.78In the amplitude of modulation of the Ho magnetic moment is 7.93 (8) μ_B. All these values are smaller than those expected for the respective free R³⁺ ions. A symmetry analysis of the magnetic structure in Tb₂Ni_1.78In is also included, as such information is missing from the original paper [Szytuła, Baran, Hoser, Kalychak, Penc & Tyvanchuk (2013). Acta Phys. Pol. A, 124, 994–997]. In addition, the results of magnetometric measurements are reported for Tm₂Ni_1.78In. The compound shows antiferromagnetic ordering below the Néel temperature of 4.5 K. Its magnetic properties are found to originate from magnetic moments localized solely on the thulium atoms (the nickel atoms remain non-magnetic in Tm₂Ni_1.78In). The reduction of rare earth magnetic moments in the ordered state in R₂Ni_1.78In (R = Tb, Ho, Er and Tm) and the change in direction of the moments indicate the influence of the crystalline electric field (CEF) on the stability of the magnetic order in the investigated compounds.

中文翻译：

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R2Ni1.78In 化合物的晶体和磁性结构（R = Tb、Ho、Er 和 Tm）

已经通过中子衍射研究了R ₂ Ni _1.78 In ( R = Ho, Er 和 Tm)的晶体和磁结构。该化合物以Mo ₂ FeB ₂型（空间群P 4/ mbm）的四方晶体结构结晶。在低温下，仅位于稀土原子上的磁矩形成由传播矢量k = [ k _x , k _x , ½]描述的反铁磁结构，其中k _x等于1/4，R = Er 和 Tm 或 0.3074 (4) 对于R= 呵呵。对于R = Ho，磁矩平行于c轴，或者对于R = Er 和 Tm ，磁矩位于 (001) 平面内。在对称性分析的基础上讨论了获得的磁结构。根据在 1.6 K 处收集的中子衍射数据确定的稀土磁矩为 6.5 (1) μ _B (Er) 和 6.09 (4) μ _B (Tm)，而在 Ho ₂ Ni _1.78 In中的非公称调制磁结构中Ho 磁矩的调制幅度为 7.93 (8) μ _B。所有这些值都小于相应游离R ^{3+ 的}预期值离子。还包括对 Tb ₂ Ni _1.78 In 中磁结构的对称性分析，因为原始论文 [Szytuła, Baran, Hoser, Kalychak, Penc & Tyvanchuk (2013) 中缺少此类信息。物理学报 波尔。A , 124 , 994–997]。此外，还报告了 Tm ₂ Ni _1.78 In的磁力测量结果。该化合物在 4.5 K 的尼尔温度以下显示出反铁磁性有序。发现其磁性源自仅位于铥原子上的磁矩（镍原子在 Tm ₂ Ni _1.78 In 中保持非磁性）。有序状态下稀土磁矩的减少R ₂ Ni _1.78 In ( R = Tb、Ho、Er 和 Tm) 和矩方向的变化表明结晶电场 (CEF) 对所研究化合物中磁序稳定性的影响。