Planar Hall effect induced spin rectification effect and its strong impact on spin pumping measurements

TL;DR

This paper reveals that the planar Hall effect can produce signals similar to pure spin currents in spin pumping measurements, potentially misleading analysis, and proposes a geometry-based method to distinguish these effects.

Contribution

It identifies a new source of spurious signals in spin pumping experiments and offers a straightforward symmetry analysis approach to differentiate genuine spin currents from Hall effect artifacts.

Findings

Rectified voltage from planar Hall effect can mimic spin current signals.

Microwave field distribution affects signal symmetry and lineshape.

A geometry is proposed to distinguish spin-charge conversion from Hall effect signals.

Abstract

Spin pumping is a technique widely used to generate the pure spin current and characterize the spin-charge conversion in various systems. The reversing sign of the symmetric Lorentzian charge current with respect to opposite magnetic field is generally accepted as the key criterion to identify its pure spin current origin. However, we herein find that the rectified voltage due to the planar Hall effect can exhibit similar spurious signal, complicating and even misleading the analysis. The distribution of microwave magnetic field and induction current has strong influence on the magnetic field symmetry and lineshape of the obtained signal. We further demonstrate a geometry where the spin-charge conversion and the rectified voltage can be readily distinguished with a straightforward symmetry analysis.