We performed systematic AC susceptibility and magnetic moment measurements to investigate the vortex dynamics and pinning in a $EuRbFe_4As_4$ single crystal as a function of temperature, frequency, and DC magnetic field. The vortex solid to vortex liquid line was determined and well fitted by $H(T_p) = H_0(1-tp)^b$ with $b=1.74-1.91$ for H // c indicating rather high pinning strength of vortex system. The field dependence of the activation energy U0 is gained within the approach of thermally activated flux creep theory. A power law dependence of $U_0 \sim H^{-a}$ with $a = -0.52$ is observed below 1T. The activation energy reaches 6700K at low fields, suggesting strong pinning in the material. Magnetic moment measurements also confirm the strong pinning in $EuRbFe_4As_4$. We show $Eu^{2+}$ magnetic ordering suppressed in magnetic fields about 3T.

中文翻译：

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EuRbFe4As4 铁基超导体的涡旋钉扎和磁相图。

我们进行了系统的交流磁化率和磁矩测量，以研究作为温度、频率和直流磁场函数的 $EuRbFe_4As_4$ 单晶中的涡流动力学和钉扎。涡流固体到涡流液体线由 $H(T_p) = H_0(1-tp)^b$ 确定并很好地拟合，H // c 的 $b=1.74-1.91$ 表明涡流系统的钉扎强度相当高。活化能 U0 的场依赖性是在热活化通量蠕变理论的方法中获得的。在 1T 以下观察到 $U_0 \sim H^{-a}$ 与 $a = -0.52$ 的幂律依赖性。在低场激活能达到 6700K，表明材料中存在强钉扎。磁矩测量也证实了 $EuRbFe_4As_4$ 中的强钉扎。我们展示了 $Eu^{2+}$ 磁序在大约 3T 的磁场中被抑制。