The distinction of time-reversal-like degeneracy by electronic transport in a new compound

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.

Figures (5)

• 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.
• 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) and (d), to more clearly demonstrate the changes in magnetic transitions, the curves have been shifted along the vertical axis.
• Figure 3: (a) and (b) Magnetic field dependent magnetization of Ce$_3$MgBi$_5$ in the $\textbf{H} \perp bc$ and $\textbf{H} \parallel b$ directions at different temperatures. (c) and (d) Magnetization curves at 1.8 K for $\textbf{H} \perp bc$ and $\textbf{H} \parallel b$ after subtracting the Van-Vleck term.
• Figure 4: (a)-(d) Schematic diagrams of the four electronic transport measurement configurations used. In (a) and (b), the magnetic field is along the $b$ axis, while the current flows along the $c$ axis ($\textbf{I} \parallel c$, perpendicular to the distorted kagome lattice) and perpendicular to the $bc$ direction ($\textbf{I} \perp bc$, parallel to the distorted kagome lattice), respectively. In (c) and (d), the magnetic field is perpendicular to the $bc$ direction, while the current flows along the $c$ axis ($\textbf{I} \parallel c$, perpendicular to the distorted kagome lattice) and $b$ axis ($\textbf{I} \parallel b$, parallel to the distorted kagome lattice), respectively. (e)-(h) Magnetic field dependent resistivity (upper panel), Hall resistivity (middle panel), and magnetization (lower panel) corresponding to four measurement configurations. The black lines and the red lines represent the measurement results of the magnetic field sweeping from $+$14 T to $-$14 T and from $-$14 T to $+$14 T, respectively. The temperature is fixed at 1.8 K. The data has been symmetrized or antisymmetrized to eliminate the influence of electrodes.
• Figure 5: (a) Model of the chirality reversal process of the toroidal moment states in HoAgGe under $\mathcal{D}$ and $\emph{R}_b^{\pi}$ operations. (b) and (c) The effects of $\mathcal{D}$ and $\emph{R}_b^{\pi}$ operations on the two sublattices of Ce$_3$MgBi$_5$.