标题： EuMn$_2$P$_2$中的磁挫和弱锰磁序 显示英文标题

标题： Magnetic frustration and weak Mn magnetic ordering in EuMn$_2$P$_2$

摘要： 我们报告了EuMn$_{2}$P$_{2}$单晶的电子顺磁共振（ESR）、比热、磁化率、核磁共振（NMR）、磁圆二色性（XMCD）和磁线二色性（XMLD），以及电导率。 在多个量中观察到了Eu的反铁磁有序，温度接近$T^{\rm Eu}_{\rm N}\,=\,18\,\rm K$时。 ESR线宽和共振位移的温度依赖性显示，在接近Eu有序态时，向$T^{\rm Eu}_{\rm N}$发散，表明磁关联的重要性增加以及内部磁场的建立。 一个额外的温度尺度$\approx 47\,\rm K$对线宽、共振场和强度有显著影响。 这表明存在弱的Mn基有序。 观测到的ESR线被解释为Eu$^{2+}$共振，它探测了Mn子系统的弱磁背景。 这种图像由在$47\,\rm K$尺度上保持为洛伦兹形的线形所提示，并由ESR强度所提示，该强度在$47\,\rm K$以上和以下都可以用相同的居里-维斯温度来描述。 在同一温度范围内，在热容量数据中也观察到了$48.5\,\rm K$和$51\,\rm K$的异常，以及 EuMn$_{2}$P$_{2}$样品的NMR信号显著展宽。 在XMCD和XMLD测量中，同一温度范围内未能检测到这种弱磁序，这可能是由于磁矩较小，具有潜在的$c$-分量或挫折。 显示英文摘要

摘要： We report on the electron spin resonance (ESR), heat capacity, magnetization, nuclear magnetic resonance (NMR), magnetic circular and linear dichroism (XMCD, XMLD), as well as the electrical resistivity of EuMn$_{2}$P$_{2}$ single crystals. Antiferromagnetic order of Eu was observed in several quantities at $T^{\rm Eu}_{\rm N}\,=\,18\,\rm K$. The temperature dependencies of ESR linewidth and resonance shift show, when approaching the Eu-ordered state, a divergence towards $T^{\rm Eu}_{\rm N}$, indicating the growing importance of magnetic correlations and the build-up of internal magnetic fields. An additional temperature scale of $\approx 47\,\rm K$ has considerable impact on linewidth, resonance field and intensity. This points to the presence of weak Mn-based ordering. The observed ESR line is interpreted as an Eu$^{2+}$ resonance, which probes the weak magnetic background of the Mn subsystem. Such picture is suggested by the lineshape which keeps to be Lorentzian across the $47\,\rm K$ scale and by the ESR intensity which can be described by the same Curie-Weiss temperature above and below $47\,\rm K$. In the same temperature range anomalies were observed at $48.5\,\rm K$ and $51\,\rm K$ in the heat capacity data as well as a pronounced broadening of the NMR signal of the EuMn$_{2}$P$_{2}$ samples. In XMCD and XMLD measurements, this weak magnetic order could not be detected in the same temperature range which might be due to the small magnetic moment, with a potential $c$-component or frustration.