Recent experiments showed that hydrogenation of ${\mathrm{U}}_2{\mathrm{Ni}}_2\mathrm{Sn}$ leads to a dramatic change of the magnetic anisotropy (MA) from strongly uniaxial type to easy-plane type with easy axis and easy plane orthogonal to each other. We applied first-principles calculations aiming to understand the microscopic origin of the drastic MA change and distinguish between discontinuous and continuous scenarios of the transformation. The calculations combined with symmetry analysis revealed that the hydrogenation leads to the instability of both uniaxial and easy-plane states caused by the reduced symmetry of the atomic lattice. The obtained noncollinear noncoplanar magnetic states have the features of both apparently competing magnetic structures, which indicates the validity of the continuous scenario of the transformation. An insight into the active interatomic interactions shows that Dzyaloshinskii-Moriya interaction contributes to magnetic transformations and must be taken into account on the same footing as MA.

中文翻译：

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氢对5f电子系统磁各向异性的剧烈影响的微观性质：以U2Ni2Sn为例

最近的实验表明， ${\mathrm{ü}}_2{你}_2锡$导致磁各向异性（MA）从强单轴型到具有易轴和易平面彼此正交的易平面型的巨大变化。我们应用第一性原理计算旨在了解剧烈MA变化的微观起源，并区分转换的不连续和连续情况。结合对称分析的计算结果表明，氢化导致原子晶格对称性降低，从而导致单轴态和易平面态的不稳定性。所获得的非共线非共面磁态具有两个明显竞争的磁性结构的特征，这表明了变换连续场景的有效性。