Evidence of interfacial asymmetric spin scattering at ferromagnet-Pt interfaces

TL;DR

This paper investigates how interfacial asymmetric spin scattering influences spin-charge interconversion at ferromagnet-Pt interfaces, revealing the dominant role of interface spin polarization and asymmetric scattering mechanisms.

Contribution

It demonstrates that interfacial asymmetric spin scattering significantly affects spin injection and detection, challenging the assumption of transparent interfaces and bulk-dominated processes.

Findings

Effective spin Hall angles vary with ferromagnetic materials.

Interface resistance is large and influential.

Interfacial asymmetric spin scattering drives spin injection.

Abstract

We measure the spin-charge interconversion by the spin Hall effect in ferromagnetic/Pt nanodevices. The extracted effective spin Hall angles (SHAs) of Pt evolve drastically with the ferromagnetic (FM) materials (CoFe, Co, and NiFe), when assuming transparent interfaces and a bulk origin of the spin injection/detection by the FM elements. By carefully measuring the interface resistance, we show that it is quite large and cannot be neglected. We then evidence that the spin injection/detection at the FM/Pt interfaces are dominated by the spin polarization of the interfaces. We show that interfacial asymmetric spin scattering becomes the driving mechanism of the spin injection in our samples.