Large anomalous Hall effect in the kagome ferromagnet LiMn$_6$Sn$_6$

TL;DR

This paper reports a large anomalous Hall effect in the kagome ferromagnet LiMn$_6$Sn$_6$, linked to band crossings near the Fermi energy, with experimental and theoretical results showing significant intrinsic Hall conductivity.

Contribution

It demonstrates a large intrinsic anomalous Hall effect in LiMn$_6$Sn$_6$, a kagome ferromagnet, and links this to band crossings near the Fermi energy through combined experiments and calculations.

Findings

Large anomalous Hall conductivity of 380 Ω^{-1} cm^{-1} observed.

Band crossings, including a Dirac point, are near the Fermi energy.

Experimental Hall conductivity matches theoretical calculations.

Abstract

Kagome magnets are believed to have numerous exotic physical properties due to the possible interplay between lattice geometry, electron correlation and band topology. Here, we report the large anomalous Hall effect in the kagome ferromagnet LiMn$_6$Sn$_6$, which has a Curie temperature of 382 K and easy plane along with the kagome lattice. At low temperatures, unsaturated positive magnetoresistance and opposite signs of ordinary Hall coefficient for $\rho_{xz}$ and $\rho_{yx}$ indicate the coexistence of electrons and holes in the system. A large intrinsic anomalous Hall conductivity of 380 $\Omega^{-1}$ cm$^{-1}$, or 0.44 $e^2/h$ per Mn layer, is observed in $\sigma_{xy}^A$. This value is significantly larger than those in other $R$Mn$_6$Sn$_6$ ($R$ = rare earth elements) kagome compounds. Band structure calculations show several band crossings, including a spin-polarized Dirac point at the K point, close to the Fermi energy. The calculated intrinsic Hall conductivity agrees well with the experimental value, and shows a maximum peak near the Fermi energy. We attribute the large anomalous Hall effect in LiMn$_6$Sn$_6$ to the band crossings closely located near the Fermi energy.