AI 中文总结
研究SmCuAs₂的低温结构与磁学性质，发现其存在磁弹耦合，Sm磁矩沿c轴呈++--堆叠，面内磁矩取向及磁阻挫是电阻率极小值的关键因素。
AI 中文摘要
我们利用高分辨率同步辐射X射线衍射及Sm L₂、L₃边的X射线共振磁散射（XRMS），研究了单晶SmCuAs₂的结构与磁学性质。变温衍射测量证实，SmCuAs₂从室温降至8 K时均保持四方对称性，晶格参数在电阻率极小值（T≈30 K）以下呈现反常行为；尤为显著的是，c轴晶格参数在奈尔温度附近出现平台后上升，表明存在磁弹耦合。XRMS测量揭示其具有传播矢量q=(0,0,0.5)的 commensurate（公度）反铁磁结构，Sm磁矩在ab面内排列，沿c轴呈++--堆叠。与相关RECuAs₂化合物（RE=Pr、Nd、Gd）的对比显示，面内磁矩取向及相关磁阻挫是电阻率极小值出现的关键因素；该系列化合物自旋轨道耦合与磁弹耦合的差异，凸显了二者在调控低温输运行为中的重要性。
英文摘要
We investigated the structural and magnetic properties of single-crystalline SmCuAs$_2$ using high-resolution synchrotron X-ray diffraction and X-ray resonant magnetic scattering (XRMS) at the Sm $L_2$ and $L_3$ edges. Temperature-dependent diffraction measurements confirm that SmCuAs$_2$ maintains its tetragonal symmetry from room temperature down to 8 K, with lattice parameters showing anomalous behavior below the resistivity minimum ($T \approx$ 30 K). Notably, the \textbf{c}-axis lattice parameter exhibits a plateau and subsequent increase near the Néel temperature, indicating magnetoelastic coupling. XRMS measurements reveal a commensurate antiferromagnetic structure with a propagation vector \textbf{\textit{q}} = (0, 0, 0.5). Our measurement shows that the Sm moments are aligned within the \textbf{\textit{ab}} plane and arranged in a $++--$ stacking along the \textbf{\textit{c}}-axis. Comparison with related \textit{RE}CuAs$_2$ compounds (\textit{RE} = Pr, Nd, and Gd) suggests that in-plane moment orientation and associated magnetic frustration play a key role in the emergence of the resistivity minimum. Differences in spin-orbit and magnetoelastic coupling across the series highlight their importance in governing low-temperature transport behavior.
Journal refPhys. Rev. B 113, 064403 (2026)
