AI 中文总结
研究Sr(Ni$_{1-x}$Co$_x$)$_2$P$_2$中磁基态性质，通过单晶中子衍射测量不同Co含量样品，发现不同x值呈现不同磁序，突出竞争基态间微妙平衡，其演化超出传统模型。
AI 中文摘要
SrNi$_2$P$_2$是A(TM)$_2$X$_2$化合物家族中结构相坍塌的独特案例。此前对Co掺杂的研究产生了磁相图，但磁基态的详细性质仍存重要问题。我们对Sr(Ni$_{1-x}$Co$_x$)$_2$P$_2$（$x = 0.88$、0.94和0.97）进行单晶中子衍射测量。$x = 0.88$和0.94时呈现非共线螺旋磁序，$x = 0.97$时显示铁磁有序基态特征。结果突出了竞争基态间的微妙平衡，其演化未被传统模型完全捕捉。
英文摘要
SrNi$_2$P$_2$ represents a unique case of a collapsed structural phase (one-third collapsed, where one out of every three P-P pairs forms a bond) in the A(TM)$_2$X$_2$ family of compounds (A = alkali metal, alkaline-earth metal, or rare earth; TM = transition metal; X = pnictogen). Furthermore, Co doping studies aimed at understanding the interrelationship between this unusual bonding motif and the resulting physical properties produced a magnetically rich phase diagram, specifically on the Co-rich side of the phase diagram. However, important questions remained regarding the detailed nature of the magnetic ground states. To address these issues, we performed single-crystal neutron diffraction measurements on Sr(Ni$_{1-x}$Co$_x$)$_2$P$_2$ with compositions $x = 0.88$, 0.94, and 0.97. For $x = 0.88$ and 0.94, the measurements reveal incommensurate helical magnetic order with a doping-dependent propagation vector $(0,0,τ)$, similar to that observed in Sr(Ni$_{1-x}$Co$_x$)$_2$As$_2$. In contrast, the $x = 0.97$ composition shows clear signatures of a ferromagnetically ordered ground state, resolving the earlier ambiguity regarding the nature of the low-temperature phase. Furthermore, our results highlight the subtle balance between these competing ground states, whose evolution does not appear to be fully captured by the conventional frameworks of either itinerant or local-moment Heisenberg models typically applied to related 122 systems.
Comments10 pages, 8 figures
