Spin-Hall-Active Platinum Thin Films Grown Via Atomic Layer Deposition

TL;DR

This paper investigates the magnetoresistance of yttrium iron garnet/Pt heterostructures with platinum layers grown by atomic layer deposition, showing ALD's potential for fabricating spin-Hall-active films suitable for 3D spintronic devices.

Contribution

It demonstrates that ALD-grown platinum films exhibit comparable spin transport properties to sputtered films, enabling conformal coatings for complex geometries in spintronics.

Findings

Spin Hall magnetoresistance observed in ALD Pt films.

Spin diffusion length of 1.5 nm matches literature.

Magnetoresistance magnitude is smaller than sputtered films.

Abstract

We study the magnetoresistance of yttrium iron garnet/Pt heterostructures in which the Pt layer was grown via atomic layer deposition (ALD). Magnetotransport experiments in three orthogonal rotation planes reveal the hallmark features of spin Hall magnetoresistance. We estimate the spin transport parameters by comparing the magnitude of the magnetoresistance in samples with different Pt thicknesses. We compare the spin Hall angle and the spin diffusion length of the ALD Pt layers to the values reported for high-quality sputter-deposited Pt films. The spin diffusion length of 1.5nm agrees well with platinum thin films reported in the literature, whereas the spin Hall magnetoresistance $\Delta \rho / \rho = 2.2\times 10^{-5}$ is approximately a factor of 20 smaller compared to that of our sputter-deposited films. Our results demonstrate that ALD allows fabricating spin-Hall-active Pt films of suitable quality for use in spin transport structures. This work provides the basis to establish conformal ALD coatings for arbitrary surface geometries with spin-Hall-active metals and could lead to 3D spintronic devices in the future.