Vector spectroscopy for spin pumping

TL;DR

This paper introduces a method to distinguish the inverse spin Hall effect from galvanomagnetic effects in spin pumping experiments by measuring dc voltages in orthogonal directions, validated through experiments on metallic bilayer systems.

Contribution

The paper presents a novel measurement technique that separates ISHE from galvanomagnetic effects in spin pumping, enhancing analysis accuracy in spintronic experiments.

Findings

ISHE signal is over five times larger than galvanomagnetic signals in Ni81Fe19/Pt.

The method's effectiveness is confirmed across different material systems, demonstrating universality.

Distinct symmetry and angular dependence help differentiate ISHE from other effects.

Abstract

We propose a method to separate the inverse spin Hall effect (ISHE) from galvanomagnetic effects in spin pumping experiments on metallic bilayer systems by measuring the dc electromotive force in two orthogonal directions. Calculations of dc voltages in longitudinal and Hall directions induced in Ni81Fe19 and Ni81Fe19/Pt films at ferromagnetic resonance in a microwave cavity predict that contributions from ISHE and from the galvanomagnetic effects, i.e. the anisotropic magnetoresistance and the anomalous Hall effect, exhibit distinct signal symmetry as well as angular dependence when changing the direction of the external field with respect to the film plane. According to measurements on Ni81Fe19/Pt, only that dc voltage component which includes ISHE is more than five times larger than purely galvanomagnetic components. This is corroborated by results on La0.67Sr0.33MnO3/Pt samples, demonstrating universality of this method.