发表机构
University of Washington; National Institute of Advanced Industrial Science and Technology (AIST)（华盛顿大学; 国立研究开发法人产业技术综合研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文利用宽场氮-空位磁强计对单个LaCrO$_3$微晶成像，在单颗粒中探测到反铁磁Néel转变，揭示了倾斜反铁磁有序和结构钉扎的磁畴，为关联颗粒形态与磁有序提供了灵敏手段。
AI 中文摘要
稀土正铬酸盐展现出丰富且可通过化学调控的磁性行为，使其在温度传感和温度依赖的开关应用中具有吸引力。实现这一潜力需要理解合成条件和颗粒形态如何影响底层Cr$^{3+}$磁有序。正铬酸盐磁性传统上通过中子衍射和SQUID磁强计等系综技术表征，这些技术仅报告平均磁性质，无法获取颗粒级信息。这里，我们使用宽场氮-空位（NV）磁强计对通过熔盐合成制备的单个LaCrO$_3$微晶的杂散磁场进行成像，在单颗粒中分辨出反铁磁Néel转变。在278至298 K之间测量的18个颗粒中，5个显示出在系综Néel温度附近磁化的清晰起始，4个显示出无可测量的磁信号，9个显示出与系综测量未检测到的局域磁性杂质一致的温度无关特征。在Néel温度以下，颗粒磁化在旋转的面内磁场下保持固定，与倾斜反铁磁有序而非顺磁性一致，而重复热循环表明磁场图案在不同冷却之间变化，某些特征在相同位置重现，与微米尺度结构钉扎的反铁磁畴一致，其中弱铁磁矩的符号在每次通过Néel转变时独立设定。这些结果确立了单粒子NV磁强计作为单个微晶中磁有序和畴结构的灵敏探针，这是将单个颗粒形态和缺陷结构与正铬酸盐中磁有序相关联的关键一步。
英文摘要
Rare-earth orthochromites exhibit rich, chemically tunable magnetic behavior, making them attractive for temperature sensing and temperature-dependent switching applications. Realizing this potential requires understanding how synthesis conditions and particle morphology influence the underlying Cr$^{3+}$ magnetic ordering. Orthochromite magnetism has traditionally been characterized by ensemble techniques such as neutron diffraction and SQUID magnetometry, which report only averaged magnetic properties and cannot access particle-level information. Here we use widefield nitrogen-vacancy (NV) magnetometry to image the stray magnetic fields of individual LaCrO$_3$ microcrystals produced via molten salt synthesis, resolving the antiferromagnetic Néel transition in single particles. Of the 18 particles measured between 278 and 298 K, five show a clear onset of magnetization near the ensemble Néel temperature, four show no measurable magnetic signal, and nine display temperature-independent signatures consistent with localized magnetic impurities undetected by ensemble measurements. Below the Néel temperature, particle magnetization remains fixed under a rotating in-plane field, consistent with canted antiferromagnetic ordering rather than paramagnetism, while repeated thermal cycling shows that the magnetic field pattern varies between cooldowns with certain features recurring at the same locations, consistent with micron-scale structurally pinned antiferromagnetic domains in which the sign of the weak ferromagnetic moment is set independently each time they pass through the Néel transition. These results establish single-particle NV magnetometry as a sensitive probe of magnetic ordering and domain structure in individual microcrystals, a key step toward correlating individual particle morphology and defect structure with magnetic ordering in orthochromites.
