Scaling of the anomalous Hall effect in Sr$_{1-x}$Ca$_x$RuO$_3$

TL;DR

This study investigates how the anomalous Hall effect in Sr$_{1-x}$Ca$_x$RuO$_3$ thin films varies with composition and temperature, revealing complex behavior and a scaling law consistent with intrinsic mechanisms based on first-principles calculations.

Contribution

It demonstrates a scaling behavior of the transverse conductivity with magnetization, supporting the intrinsic origin of the AHE in these materials.

Findings

Transverse resistivity varies non-monotonously with temperature and can change sign.

Scaling of transverse conductivity with magnetization is observed.

First-principles calculations support the intrinsic mechanism of AHE.

Abstract

The anomalous Hall effect (AHE) of ferromagnetic thin films of Sr$_{1-x}$Ca$_{x}$RuO$_3$ (0 $\leq x \leq$ 0.4) is studied as a function of $x$ and temperature $T$. As $x$ increases, both the transition temperature $T_c$ and the magnetization $M$ are reduced and vanish near $x \sim$ 0.7. For all compositions, the transverse resistivity $\rho_{H}$ varies non-monotonously with $T$, and even changes sign, thus violating the conventional expression $\rho_{H}=R_o B + 4\pi R_s M(T)$ ($B$ is the magnetic induction, while $R_o$ and $R_s$ are the ordinary and anomalous Hall coefficients). From the rather complicated data of $\rho_H$, we find a scaling behavior of the transverse conductivity $\sigma_{xy}$ with $M(T)$, which is well reproduced by the first-principles band calculation assuming the intrinsic origin of the AHE.