Chiral spin spiral in synthetic antiferromagnets probed by circular dichroism in x-ray resonant magnetic scattering

TL;DR

This paper demonstrates that circular dichroism in x-ray resonant magnetic scattering can directly characterize chiral spin textures in synthetic antiferromagnets, revealing their period, type, chirality, and temperature stability.

Contribution

It introduces a novel application of CD-XRMS for directly probing magnetic SAF textures, including their chirality and temperature dependence, overcoming limitations of standard techniques.

Findings

CD-XRMS can determine SAF spin texture parameters.

Temperature affects the stability and exchange interactions of SAF spin spirals.

Chiral spin textures in SAF are stable down to 40K.

Abstract

Noncollinear chiral spin textures in ferromagnetic multilayers are at the forefront of recent research in nano-magnetism with the promise for fast and energy-efficient devices. The recently demonstrated possibilities to stabilize such chiral structures in synthetic antiferromagnets (SAF) has raised interests as they are immune to dipolar field, hence favoring the stabilization of ultra small textures, improve mobility and avoid the transverse deflections of moving skyrmions limiting the efficiency in some foreseen applications. However, such systems with zero net magnetization are hence difficult to characterize by most of the standard techniques. Here, we report that the relevant parameters of a magnetic SAF texture, those being its period, its type (N\'eel or Bloch) and its chirality (clockwise or counterclockwise), can be directly determined using the circular dichroism in x-ray resonant scattering (CD-XRMS) at half integer multilayer Bragg peaks in reciprocal space. The analysis of the dependence in temperature down to 40K allows us moreover to address the question of the temperature stability of a spin spiral in a SAF sample and of the temperature scaling of the symmetric and antisymmetric exchange interactions.