Magnetic domain walls in strain-patterned ultrathin films

TL;DR

This study compares magnetic domain walls in two strain-patterned ultrathin films, revealing how structural patterns influence domain wall configurations and the role of Dzyaloshinskii-Moriya interactions.

Contribution

It provides a detailed comparison of domain wall characteristics in Co/Pt(111) and Ni/Fe/Ir(111) films, highlighting the impact of structural patterns on magnetic behavior.

Findings

Domain walls in Co/Pt are straight and minimize length in constrictions.

In Ni/Fe/Ir, domain walls follow complex paths linked to structural patterns.

Structural patterns differently influence magnetic states in the two systems.

Abstract

We present a comparison of the characteristics of the magnetic domain walls in an atomic monolayer of Co on Pt(111) and a Ni/Fe atomic bilayer on Ir(111), based on spin-polarized scanning tunneling microscopy measurements. In both cases, the films exhibit a roughly triangular dislocation line pattern created by epitaxial strain relief, as well as out-of-plane ferromagnetic order. Domains with opposite magnetization are separated by domain walls with a unique rotational sense, demonstrating the important role of the Dzyaloshinskii-Moriya interaction induced by the Co/Pt and the Fe/Ir interfaces. The domain walls in Co/Pt(111) are straight and usually found in geometrical constrictions of the film, where they can minimize their length. In contrast, the domain walls in Ni/Fe/Ir(111) follow complicated paths, which can be correlated to the structural triangular pattern. The comparison between the two systems shows that the structural patterns, despite their similarity, have a different impact on the domain walls. In the Co/Pt(111) case, the magnetic state is not influenced by the dislocation line network, in contrast to the Ni/Fe/Ir(111) system in which the formation of the walls is favored at specific positions of the structural pattern.