Revealing the structural distortion of rare-earth Gd at low temperature

Our lab. XRD indicates that rare earth Gd metal undergoes slightly Bragg peak broadening at low temperature, indicating a possible new phase at low temperature that has not been reported before. Our first-principles many-body calculations for the correlated 4f-shell of Gd predict that an orthorhombic phase could be stabilized by magneto-elastic forces due to ordering of Gd quadrupolar moments. Further high-resolution synchrotron XRD at ID22 is highly preferred to directly characterize the low-temperature structural distortion and reveal the low-symmetric structure. The determination of the true structure of pure Gd metal is important to further understand the nature of rare earth, such as electron structure, energy bands, phonons, and magnetism.

本课题组的X射线衍射（X-ray Diffraction, XRD）测试结果表明，稀土金属钆在低温条件下出现了轻微的布拉格峰展宽现象，暗示其低温下存在此前尚未见诸报道的全新物相。针对钆的关联4f电子壳层，我们开展的第一性原理多体计算（first-principles many-body calculations）预测，正交晶相（orthorhombic phase）可通过钆四极矩（quadrupolar moments）有序化引发的磁弹性力（magneto-elastic forces）作用得以稳定。后续亟需借助ID22线站的高分辨同步辐射X射线衍射（synchrotron XRD）实验，以直接表征低温结构畸变并解析低对称晶体结构。精准解析纯钆金属的真实晶体结构，对于深入理解稀土材料的本质特性，包括电子结构、能带结构、声子特性与磁性，具有重要的科学意义。