Metamagnetism and anomalous magnetotransport properties in rare-earth-based polar semimetals $R$AuGe ($R =$ Dy, Ho, and Gd)

TL;DR

This study investigates the magnetic, magnetoelastic, and magnetotransport properties of polar semimetals RAuGe (R=Dy, Ho, Gd), revealing complex magnetic phases, anomalous Hall effects, and high magnetoresistance linked to Berry curvature effects.

Contribution

It provides new insights into the magnetic phase diagrams, magnetotransport behavior, and intrinsic anomalous Hall effects in polar RAuGe semimetals, highlighting the role of Berry curvature.

Findings

Multi-step metamagnetic transitions indicate magnetic frustration.

Large magnetoresistance (~345%) at low temperature and high field.

Intrinsic anomalous Hall conductivity suggests Berry curvature influence.

Abstract

We report the magnetic, magnetoelastic, and magnetotransport properties of single crystals of polar magnets $R$AuGe ($R=$ Dy, Ho, and Gd), grown by Au-Ge self-flux. Magnetization and magnetostriction measurements reveal multi-step metamagnetic transitions for the $c$-axis magnetic field ($H\parallel c$) for DyAuGe and HoAuGe, suggesting magnetic frustration in the triangular lattice of $R$ ions. The magnetic phase diagrams have clarified a close connection between the magnetoelastic property and the emergence of the intermediate metamagentic phase. The magnetic-field dependence of the resistivity and Hall resistivity reveal the semimetallic transport dominated by hole-type carriers, consistent with the behavior in a nonmagnetic analogue YAuGe. We also identify a signature of an anomalous Hall effect (AHE) proportional to the field-induced magnetization in $R=$ Dy, Ho, and Gd. GdAuGe shows magnetic and transport behavior as reported in a previous study using Bi-flux grown single crystals, while the self-flux grown crystal shows larger magnetoresistance ($\sim$ 345\%, at 1.8 K and 9 T) due to higher hole-type carrier mobility ($\sim$ 6400 cm$^2$/Vs). Using the two-band model analysis considering the mobility change during the magnetization process, we extract the anomalous Hall conductivity: $\sim 1200$ S/cm and $\sim 530$ S/cm for $R=$ Dy and Ho, respectively, at 1.8 K with 9 T for $H\parallel c$. The magnitude of conductivity suggests a contribution of intrinsic origin, possibly related to the Berry curvature in the electron bands induced by the time-reversal symmetry breaking and the polar lattice.