Extraction of Dzyaloshinksii-Moriya interaction from propagating spin waves validated

TL;DR

This paper demonstrates a method using all-electrical Propagating Spin Wave Spectroscopy to accurately quantify interfacial Dzyaloshinksii-Moriya interaction across various film thicknesses, revealing key effects of stack order and crystalline phases.

Contribution

It introduces a novel approach to disentangle multiple contributions to spin wave non-reciprocity for precise iDMI measurement in thin films.

Findings

Sign change of iDMI with stack inversion

Negligible iDMI in symmetric Pt/Co/Pt stacks

Crystalline phases significantly affect surface anisotropies

Abstract

The interfacial Dzyaloshinksii-Moriya interaction (iDMI) is of great interest in thin-film magnetism because of its ability to stabilize chiral spin textures. It can be quantified by investigating the frequency non-reciprocity of oppositely propagating spin waves. However, as the iDMI is an interface interaction the relative effect reduces when the films become thicker making quantification more difficult. Here, we utilize all-electrical Propagating Spin Wave Spectroscopy (PSWS) to disentangle multiple contributions to spin wave frequency non-reciprocity to determine the iDMI. This is done by investigating non-reciprocities across a wide range of magnetic layer thicknesses (from 4 to 26 nm) in Pt/Co/Ir, Pt/Co/Pt, and Ir/Co/Pt stacks. We find the expected sign change in the iDMI when inverting the stack order, and a negligible iDMI for the symmetric Pt/Co/Pt. We additionally extract a difference in surface anisotropies and find a large contribution due to the formation of different crystalline phases of the Co, which is corroborated using nuclear magnetic resonance and high-resolution transmission-electron-microscopy measurements. These insights will open up new avenues to investigate, quantify and disentangle the fundamental mechanisms governing the iDMI, and pave a way towards engineered large spin-wave non-reciprocities for magnonic applications.