[论文解读] The distinction of time-reversal-like degeneracy by electronic transport in a new compound

Yi-Yan Wang, Ping Su+10 more|arXiv (Cornell University)|Feb 16, 2026

Superconductivity in MgB2 and Alloys被引用 0

一句话总结

该研究报告了具有扭曲的 kagome Ce 层的反铁磁化合物 Ce3MgBi5，揭示了通过电子传输区分的近似时间反演对称性简并态，特别是在1/2 磁化平台上表现出 MR 和霍尔效应的滞后，而磁化滞后不存在。

ABSTRACT

We report the discovery of a new compound, Ce$_3$MgBi$_5$, and reveal the hidden time-reversal-like degenerate states within it. Ce$_3$MgBi$_5$ is an antiferromagnet with the distorted kagome lattice of Ce atoms, in which several fractional magnetization plateaus emerge with the increase of magnetic field. At the 1/2 magnetization plateau, obvious hysteresis has been observed in the magnetoresistance and Hall resistivity during the rise and fall of the magnetic field. However, hysteresis vanishes in the corresponding measurements of magnetization, indicating the existence of degenerate states with the same net magnetization but different electronic transport properties. The degenerate states can be connected by the time-reversal-like operation. In addition, by comparing with HoAgGe, it is suggested that the special crystal structure in Ce$_3$MgBi$_5$ may have a shielding effect on the time-reversal-like operation, thereby affecting the distinction of degenerate states. Our work establishes Ce$_3$MgBi$_5$ as an example of utilizing electronic transport properties to identify and distinguish hidden symmetries in frustrated magnetic systems.

研究动机与目标

• 识别并表征 Ce3MgBi5 的晶体结构与磁性特征。
• 研究分数磁化平台及其潜在自旋态。
• 利用电子传输测量检测隐藏的近似时间反演对称性简并态。
• 将 Ce3MgBi5 与 HoAgGe 进行比较，以理解晶体结构对时间反演类作用的影响。

提出的方法

• 合成 Ce3MgBi5 的单晶并确定晶体结构。
• 测量磁化率以识别反铁磁相变和各向异性。
• 记录场依赖的磁化以观察分数磁化平台。
• 进行四种电子传输配置以测量电阻率和霍尔效应以及磁化。
• 分析 MR 和霍尔效应对磁化的滞后，识别近似时间反演对称性简并性。
• 将实验结果与 HoAgGe 进行比较，讨论结构屏蔽效应。

Figure 1: (a) Crystal structure of Ce 3 MgBi 5 viewed from the $c$ -axis direction. (b) Two alternately stacked distorted kagome lattice layers composed of Ce atoms. (c) Schematic diagram of the crystal axis directions. The long axis direction is perpendicular to the distorted kagome lattice layers.

实验结果

研究问题

• RQ1 Ce3MgBi5 是否在传输测量中揭示隐藏的近似时间反演类简并态？
• RQ2 在哪些磁化平台上 MR 滞后和霍尔电阻滞后出现或消失，原因何在？
• RQ3 Ce3MgBi5 的晶体堆叠结构如何影响相较于 HoAgGe 的时间反演类作用？
• RQ4 圆环矩量（torodial moment）手性与 Ce3MgBi5 的电子传输之间有什么关系？

主要发现

• Ce3MgBi5 为具有扭曲 kagome Ce 晶格的反铁磁体，并显示出若干分数磁化平台。
• 在1/2 磁化平台处观测到 MR 和霍尔电阻的显著滞后，但磁化滞后不存在，指示隐藏的近似时间反演类简并态。
• 这些简并态可以通过时间反演类作用相连，该作用改变 Berry 曲率与电子传输，但不改变净磁化。
• Ce3MgBi5 的特殊晶体结构可能屏蔽时间反演类作用，降低其效应相较于 HoAgGe，从而影响哪些平台显示出滞后。

Figure 2: (a) The ZFC-FC magnetic susceptibility of Ce 3 MgBi 5 with applying 100 Oe magnetic field in the directions of $\textbf{H}\perp bc$ , $\textbf{H}\parallel b$ and $\textbf{H}\parallel c$ . (b)-(d) The ZFC-FC $\chi(T)$ curves under various magnetic fields in these three directions. In (c) an