Disorder driven crossover between anomalous Hall regimes in Fe$_3$GaTe$_2$

TL;DR

This study reveals how disorder influences the anomalous Hall conductivity in Fe$_3$GaTe$_2$, showing a crossover from disorder-dependent to intrinsic behavior as conductivity increases, supported by experimental and theoretical analysis.

Contribution

It demonstrates the disorder-driven crossover between different anomalous Hall regimes in Fe$_3$GaTe$_2$, combining experimental measurements with DFT calculations to elucidate the underlying mechanisms.

Findings

Intrinsic AHC is disorder-independent with a high value of ~420 Ω^{-1}cm^{-1}.

Scaling relation σ_{xy} ∝ σ_{xx}^{1.6} observed in low-conductivity regime.

Crossover from disorder-dependent to intrinsic AHC as conductivity increases.

Abstract

The large anomalous Hall conductivity (AHC) of the Fe$_3$(Ge,Ga)Te$_2$ compounds has attracted considerable attention. Here, we expose the intrinsic nature of AHC in Fe$_3$GaTe$_2$ crystals characterized by high conductivities, which show disorder-independent AHC with a pronounced value $\sigma_{xy}^{\text{c}}\approx$ 420 $\Omega^{-1}$cm$^{-1}$. In the low conductivity regime, we observe the scaling relation $\sigma_{xy}\propto\sigma_{xx}^{1.6}$, which crosses over to $\sigma_{xy} \simeq \sigma_{xy}^{\text{c}}$ as $\sigma_{xx}$ increases. Disorder in low-conductivity crystals is confirmed by the broadening of a first-order transition between ferromagnetism and the ferrimagnetic ground state. Through density functional theory (DFT) calculations, we reveal that the dominant sources of Berry curvature are located a few hundred meV below the Fermi energy around the $\Gamma$-point. Therefore, Fe$_3$GaTe$_2$ clearly exposes the disorder-induced crossover among distinct AHC regimes, previously inferred from measurements on different ferromagnets located in either side of the crossover region.