arXiv subjects

MacCallum Robertson

Publications and source records attributed to MacCallum Robertson.

3 recordsLinked to original sources

arXiv2021

Chirality-induced zigzag domain wall in in-plane magnetized ultrathin films

The domain structure in in-plane magnetized Fe/Ni/W(110) films is investigated using spin-polarized low-energy electron microscopy. A novel transition of the domain wall shape from a zigzag-like pattern to straight is observed as a function of the film thickness, which is triggered by the transition of the domain wall type from out-of-plane chiral wall to in-plane N\'eel wall. The contribution of the Dzyaloshinskii-Moriya interaction to the wall energy is proposed to explain the transition of the domain wall shape, which is supported by Monte-Carlo simulations.

cond-mat.mes-hall↗

arXiv2021

Observation of hydrogen-induced Dzyaloshinskii-Moriya interaction and reversible switching of magnetic chirality

The Dzyaloshinskii-Moriya interaction (DMI) has drawn great attention as it stabilizes magnetic chirality, with important implications in fundamental and applied research. This antisymmetric exchange interaction is induced by the broken inversion symmetry at interfaces or in non-centrosymmetric lattices. Significant interfacial DMI was found often at magnetic / heavy-metal interfaces with large spin-orbit coupling. Recent studies have shown promise of induced DMI at interfaces involving light elements such as carbon (graphene) or oxygen. Here we report direct observation of induced DMI by chemisorption of the lightest element, hydrogen, on a ferromagnetic layer at room temperature, which is supported by density functional theory calculations. We further demonstrate a reversible chirality transition of the magnetic domain walls due to the induced DMI via hydrogen chemisorption/desorption. These results shed new light on the understanding of DMI in low atomic number materials and design of novel chiral spintronics and magneto-ionic devices.

cond-mat.mtrl-sci↗

arXiv2020

In-plane Néel wall chirality and orientation of interfacial Dzyaloshinskii-Moriya vector in magnetic films

The interfacial Dzyaloshinskii-Moriya interaction (DMI) is of great interest as it can stabilize chiral spin structures in thin films. Experiments verifying the orientation of the interfacial DMI vector remain rare, in part due to the difficulty of separating vector components of DMI. In this study, Fe/Ni bilayers and Co/Ni multilayers were deposited epitaxially onto Cu(001) and Pt(111) substrates, respectively. By tailoring the effective anisotropy, spin reorientation transitions (SRTs) are employed to probe the orientation of the DMI vector by measuring the spin structure of domain walls on both sides of the SRTs. The interfacial DMI is found to be sufficiently strong to stabilize chiral Néel walls in the out-of-plane magnetized regimes, while achiral Néel walls are observed in the in-plane magnetized regimes. These findings experimentally confirm that the out-of-plane component of the DMI vector is insignificant in these fcc(001) and fcc(111) oriented interfaces, even in the presence of atomic steps.

cond-mat.mtrl-sci↗