Rare earth monogallide (REGa) Zintl phases are attractive for their properties in hydrogen storage and magnetic cooling. However, the magnetic effects upon hydrogen additions in REGa are not well understood. This study aims to explore the magnetic effects in ${\mathrm{REGaH}}_{\mathrm{x}}$ using SQUID magnetometry and neutron powder diffraction. To avoid challenges due to absorption and high incoherent scattering in the neutron diffraction experiments, the compound ${\mathrm{NdGaD}}_x$ ($x$ = 0, 0.9, or 1.6) was chosen for examination. It was found that NdGa exhibits two ferromagnetic structures below the Curie temperature of 42 K. Just below 42 K the magnetic moments are oriented along the crystallographic $c$ axis, and at 20 K a spin reorientation occurs where the moments turn $\sim {30}^{\circ }$ toward the $a$ axis. Upon partial deuteration ($x$ = 0.9), the magnetization decreases and two magnetic phases are observed, one intermediate incommensurate phase, and one canted ferromagnetic phase with the net magnetization aligning along the $b$ axis. For the full deuteride ($x$ = 1.6) only one incommensurate magnetic phase is observed at low temperatures. Magnetometry also reveals that there are no isotope effects when absorbing H or D. The absorption of H or D changes the Nd-Nd distances as well as the electronic structure, which results in a drastic change in the magnetic properties as compared to NdGa.

中文翻译：

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NdGa吸氢后磁性能的变化

稀土单镓酸钾 (REGa) Zintl 相因其在储氢和磁冷却方面的特性而极具吸引力。然而，REGa 中加氢的磁效应尚不清楚。本研究旨在探讨磁效应${\mathrm{雷加赫}}_{\mathrm{X}}$使用 SQUID 磁力测量和中子粉末衍射。为了避免中子衍射实验中吸收和高非相干散射带来的挑战，该化合物${\mathrm{铷镓}}_X$（$X$= 0、0.9 或 1.6）被选择进行检查。研究发现，NdGa 在 42 K 居里温度以下呈现出两种铁磁结构。在 42 K 以下，磁矩沿着晶体取向$C$轴，并且在 20 K 时，力矩转向处会发生自旋重新定向$～{30}^{\circ }$朝向$A$轴。部分氘化后（$X$= 0.9），磁化强度降低，观察到两个磁相，一个中间不相称相，和一个倾斜的铁磁相，净磁化强度沿$乙$轴。对于完全氘化物（$X$= 1.6) 在低温下仅观察到一种不相称的磁相。磁力测定还表明，吸收 H 或 D 时不存在同位素效应。吸收 H 或 D 会改变 Nd-Nd 距离以及电子结构，从而导致与 NdGa 相比磁性能发生巨大变化。