Increased magnetic damping of a single domain wall and adjacent magnetic domains detected by spin torque diode in a nanostripe

TL;DR

This study uses spin-torque resonance to measure magnetic damping in nanostripe magnetic tunnel junctions, revealing a doubling of damping in domain walls and domains, attributed to intrinsic effects of localized excitations.

Contribution

It provides the first quantitative analysis of damping in single domain walls and magnetic domains, highlighting intrinsic damping mechanisms beyond dipolar and spin pumping effects.

Findings

Damping of domains and domain walls is doubled compared to the host layer.

Dipolar couplings and spin pumping do not account for the damping increase.

Intrinsic effects of localized modes cause the observed damping enhancement.

Abstract

We use spin-torque resonance to probe simultaneously and separately the dynamics of a magnetic domain wall and of magnetic domains in a nanostripe magnetic tunnel junction. Thanks to the large associated resistance variations we are able to analyze quantitatively the resonant properties of these single nanoscale magnetic objects. In particular, we find that the magnetic damping of both domains and domain walls is doubled compared to the damping value of their host magnetic layer. We estimate the contributions to damping arising from dipolar couplings between the different layers in the junction and from the intralayer spin pumping effect. We find that they cannot explain the large damping enhancement that we observe. We conclude that the measured increased damping is intrinsic to large amplitudes excitations of spatially localized modes or solitons such as vibrating or propagating domain walls