DyCuAs$_2$中的反铁磁有序与晶格响应
Antiferromagnetic order and lattice response in DyCuAs$_2$
AI总结：
本研究通过同步辐射X射线衍射与XRMS表征DyCuAs$_2$的低温结构与磁有序，揭示其强磁弹性耦合与$Γ_{10}$型反铁磁结构，阐明面内反铁磁有序、磁阻挫及磁弹性、自旋-轨道作用对RECuAs$_2$家族电阻率极小值的影响。
AI中文摘要：
我们报道了对DyCuAs$_2$低温晶体结构与磁结构的高分辨率同步辐射X射线衍射及X射线共振磁散射（XRMS）研究，DyCuAs$_2$是RECuAs$_2$家族的成员，该体系在反铁磁转变温度以上存在电阻率极小值现象。同步辐射衍射测量表明，在实验分辨率范围内，DyCuAs$_2$在低温下仍保持四方对称性，不过在反铁磁转变温度$T_{\text{N}}\thickapprox7$ K附近，晶格参数$a$和$c$均出现显著异常，说明存在强磁弹性耦合。Dy $L_3$边的XRMS测量证实，体系在$T_{\text{N}}$以下形成公度反铁磁有序，反铁磁布拉格峰位于\textbf{q} = (0, 0, 0.5)处。通过表示分析与反铁磁布拉格峰强度计算，确定其磁结构属于$Γ_{10}$表示，由面内Dy磁矩沿\textbf{c}轴以$++--$序列堆叠构成，因此该磁结构与此前报道的SmCuAs$_2$的磁结构完全相同。对比DyCuAs$_2$、SmCuAs$_2$和GdCuAs$_2$的结果可知，面内反铁磁有序及四方晶格上伴随的磁阻挫，与RECuAs$_2$家族中电阻率极小值的出现密切相关。同时，DyCuAs$_2$中观测到的增强晶格响应与更强的磁场敏感性表明，磁弹性相互作用与自旋-轨道耦合在决定这一反常输运行为的稳定性方面也发挥着重要作用。
英文摘要：
We report high-resolution synchrotron X-ray diffraction and X-ray resonant magnetic scattering (XRMS) studies of the low-temperature crystal and magnetic structures of DyCuAs$_2$, a member of the \RE{}CuAs$_2$ family exhibiting a resistivity minimum above the antiferromagnetic transition temperature. Synchrotron diffraction measurements reveal that DyCuAs$_2$ preserves tetragonal symmetry down to low temperature within the experimental resolution, although pronounced anomalies in both lattice parameters $a$ and $c$ are observed near the antiferromagnetic transition temperature, $T_{\mathrm N}\approx7$~K, indicating strong magnetoelastic coupling. XRMS measurements at the Dy $L_3$ edge establish commensurate antiferromagnetic ordering below $T_{\mathrm N}$ with AFM Bragg peaks at \qq{} = (0, 0, 0.5). Representation analysis and calculations of the AFM Bragg peak intensities identify the magnetic structure as the $Γ_{10}$ representation, consisting of in-plane Dy moments stacked along the \cc{} axis in a $++--$ sequence. The magnetic structure is therefore identical to that previously reported for SmCuAs$_2$. Comparison among DyCuAs$_2$, SmCuAs$_2$, and GdCuAs$_2$ suggests that in-plane AFM order and the associated magnetic frustration on the tetragonal lattice are closely connected to the emergence of the resistivity minimum in the \RE{}CuAs$_2$ family. At the same time, the enhanced lattice response and stronger magnetic-field sensitivity observed in DyCuAs$_2$ imply that magnetoelastic and spin-orbit interactions additionally play important roles in determining the robustness of this anomalous transport behavior.
