# Unconventional anomalous Hall effect in 3d/5d multilayers mediated by the nonlocal spin-conductivity

## TL;DR

This paper reports an unconventional anomalous Hall effect in 3d/5d multilayers caused by opposite spin-orbit coupling signs, with detailed spin-current transport analysis revealing the underlying mechanisms.

## Contribution

It introduces a novel AHE inversion in multilayers due to nonlocal spin-conductivity and provides quantitative spin Hall angles through advanced simulations.

## Key findings

- Opposite sign of spin Hall angles in Pt and (Co/Ni) layers.
- Effective AHE inversion observed for multilayers with N<17.
- Spin-current leakage and interface scattering explain the effect.

## Abstract

We evidenced unconventionnal Anomalous Hall Effects (AHE) in 3d/5d (Co0.2nm/Ni0.6nm)N multilayers grown on a thin Pt layer or thin Au:W alloy. The inversion observed on AHE originates from the opposite sign of the spin-orbit coupling of Pt compared to Ni. Via advanced simulations methods for the description of the spin-current profiles based on the spin-dependent Boltzmann formalism, we extracted the spin Hall angle (SHA) of Pt and (Co/Ni) as well as the relevant transport parameters. The extracted SHA for Pt, +20%, is opposite to the one of (Co/Ni), giving rise to an effective AHE inversion for thin (Co/Ni) multilayers (N < 17). The spin Hall angle in Pt is found to be larger than the one previously measured in combined spin-pumping inverse spin-Hall effect experiments in a geometry of current perpendicular to plane. Whereas magnetic proximity effects cannot explain the effect, spin-current leakage and anisotropic electron scattering at Pt/(Co,Ni) interfaces fit the experiments.