[Paper Review] 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 Alloys0 citations

TL;DR

The study reports a new antiferromagnetic compound Ce3MgBi5 with distorted kagome Ce layers, revealing time-reversal-like degenerate states distinguished via electronic transport, notably showing hysteresis in MR and Hall effect at the 1/2 magnetization plateau while magnetization hysteresis is absent.

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.

Motivation & Objective

• Identify and characterize the crystal structure and magnetic properties of Ce3MgBi5.
• Investigate fractional magnetization plateaus and their underlying spin states.
• Use electronic transport measurements to detect hidden time-reversal-like degenerate states.
• Compare Ce3MgBi5 with HoAgGe to understand crystal-structure effects on time-reversal-like operations.

Proposed method

• Synthesize single crystals of Ce3MgBi5 and determine crystal structure.
• Measure magnetic susceptibility to identify AFM transition and anisotropy.
• Record field-dependent magnetization to observe fractional magnetization plateaus.
• Perform four electronic transport configurations to measure resistivity and Hall effect alongside magnetization.
• Analyze hysteresis in MR and Hall effect vs. magnetization to identify time-reversal-like degeneracy.
• Compare experimental results with HoAgGe to discuss structural shielding effects.

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.

Experimental results

Research questions

• RQ1 Do Ce3MgBi5 exhibits hidden time-reversal-like degenerate states as inferred from transport measurements?
• RQ2 At which magnetization plateaus do hysteresis in MR and Hall resistivity appear or vanish, and why?
• RQ3 How does the crystal stacking in Ce3MgBi5 influence time-reversal-like operations compared to HoAgGe?
• RQ4 What is the relationship between toroidal moment chirality and electronic transport in Ce3MgBi5?

Key findings

• Ce3MgBi5 is an antiferromagnet with a distorted kagome Ce lattice and shows several fractional magnetization plateaus.
• Significant hysteresis in magnetoresistance and Hall resistivity is observed at the 1/2 magnetization plateau, but magnetization hysteresis is absent, indicating hidden time-reversal-like degenerate states.
• The degenerate states can be connected by a time-reversal-like operation that alters Berry curvature and electronic transport but not net magnetization.
• The special crystal structure of Ce3MgBi5 may shield the time-reversal-like operation, reducing its effectiveness compared to HoAgGe, affecting which plateaus show hysteresis.

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