Skip to main content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Domain-wall motion and interfacial Dzyaloshinskii-Moriya interactions in Pt/Co/Ir(tIr)/Ta multilayers

Published

Author(s)

Kowsar Shahbazi, Joo-Von Kim, Hans T. Nembach, Justin M. Shaw, Andreas Bischof, Marta Rossell, Vincent Jeudy, Thomas A. Moore, Christopher H. Marrows

Abstract

The interfacial Dzyaloshinskii-Moriya interaction (DMI) is important for chiral domain walls (DWs) and for stabilizing magnetic skyrmions. We study the effects of introducing increasing thicknesses of Ir, from zero to 2 nm, into a Pt/Co/Ta multilayer between the Co and Ta layers. There is a marked increase in magnetic moment, due to the suppression of the dead layer at the interface with Ta, but the perpendicular anisotropy is hardly affected. All samples show a universal scaling of the field-driven DW velocity across the creep and depinning regimes. Asymmetric bubble expansion shows that DWs in all of the samples have the left-handed Neel form. The value of in-plane magnetic field at which the creep velocity shows a minimum drops markedly on the introduction of Ir, as does the frequency shift of the Stokes and anti-Stokes peaks in Brillouin light scattering (BLS) measurements. Despite this qualitative similarity, there are quantitative differences in the DMI strength given by the two measurements, with BLS often returning higher values. Many features in bubble expansion velocity curves do not fit simple models commonly used, namely a lack of symmetry about the velocity minimum and no difference in velocities at high in-plane fields. These features are explained by the use of a new model in which the depinning field is allowed to vary with in-plane field in a way determined from micromagnetic simulations. This theory shows that the velocity minimum underestimates the DMI field, consistent with BLS giving higher values. Our results suggest that the DMI at an Ir/Co interface has the same sign as the DMI at a Pt/Co interface.
Citation
Physical Review B
Volume
99

Keywords

Dzyaloshinskii-Moriya Interaction, Brillouin Light Scattering, Domain Wall Motion, Skyrmions
Created March 7, 2019, Updated June 11, 2020