In ultrathin ferromagnetic films sandwiched between two distinct heavy metal layers or between a heavy metal and an oxide layer, the Dzyaloshinskii-Moriya interaction (DMI) is of interfacial origin. Its chirality and strength are determined by the properties of the adjacent heavy metals and the degree of oxidation at the interfaces. Here, we demonstrate that the DMI chirality can change solely with variations in the thickness of the ferromagnetic layer - an effect that has not been experimentally studied in details or explained until now. Our experimental observation in the trilayer system Ta/FeCoB/TaOx is supported by ab initio calculations: they reveal that variations in orbital filling and inter-atomic distances at the interface, driven by the structural relaxations in the ultrathin regime, lead to an inversion of DMI chirality. We hence propose a new degree of freedom to tune DMI chirality and the associated chiral spin textures by tailoring crystal structure e.g. using strain or surface acoustic waves.
@article{arxiv.2501.12098,
title = {Dzyaloshinskii-Moriya interaction chirality reversal with ferromagnetic thickness},
author = {Capucine Gueneau and Fatima Ibrahim and Johanna Fischer and Libor Vojáček and Charles-Élie Fillion and Stefania Pizzini and Laurent Ranno and Isabelle Joumard and Stéphane Auffret and Jérôme Faure-Vincent and Claire Baraduc and Mairbek Chshiev and Hélène Béa},
journal= {arXiv preprint arXiv:2501.12098},
year = {2026}
}