Anomalous Magnetotransport in the Paramagnetic State of a Magnetic Kagome Metal EuTi$_3$Bi$_4$

TL;DR

EuTi3Bi4 exhibits unusual magnetotransport behaviors in its paramagnetic phase, including linear magnetoconductivity and Hall sign change, likely due to multiband effects or van Hove singularities, distinct from typical magnetic or CDW-related phenomena.

Contribution

This study reveals anomalous magnetotransport in EuTi3Bi4's paramagnetic state, highlighting behaviors similar to CDW phases without the presence of charge density waves.

Findings

Linear magnetoconductivity below 1 T

Hall conductivity sign change below 2 T

Absence of charge density wave in EuTi3Bi4

Abstract

We investigate the electrical transport properties of a magnetic kagome metal EuTi$_3$Bi$_4$, which undergoes magnetic ordering below $T_\mathrm{c}=10.5$ K. Unlike typical magnets showing anomalous magnetotransport in their ordered states, EuTi$_3$Bi$_4$ exhibits unusual magnetotransport behaviors in its paramagnetic phase. Specifically, the magnetoconductivity shows a linear dependence on magnetic field at low fields below $\sim 1$ T, and the Hall conductivity undergoes a sign change below about 2 T. These behaviors resemble those observed in the charge density wave (CDW) phase of kagome metals $A$V$_3$Sb$_5$ ($A$ = K, Rb, Cs). The anomalous magnetotransport in $A$V$_3$Sb$_5$ has commonly been attributed to the possible emergence of a time-reversal symmetry breaking chiral CDW order. However, given the absence of CDW in EuTi$_3$Bi$_4$ and its manifestation exclusively in the paramagnetic state, the anomalous magnetotransport observed in EuTi$_3$Bi$_4$ is likely associated with multiband transport and/or the van Hove singularities near the Fermi level.