Magnetic non-contact friction from domain wall dynamics actuated by oscillatory mechanical motion

TL;DR

This study uses micromagnetic simulations to analyze magnetic non-contact friction caused by domain wall dynamics driven by oscillatory mechanical motion, revealing conditions where magnetic friction is comparable to other non-contact friction types.

Contribution

It introduces a simulation approach to study magnetic friction via domain wall dynamics under mechanical oscillations, highlighting the influence of micromagnetic parameters on damping.

Findings

Magnetic friction magnitude can match other non-contact friction forms.

Damping coefficient is frequency-independent below certain oscillation frequencies.

Results are relevant for experimental setups operating in 100 kHz range.

Abstract

Magnetic friction is a form of non-contact friction arising from the dissipation of energy in a magnet due to spin reorientation in a magnetic field. In this paper we study magnetic friction in the context of micromagnetics, using our recent implementation of smooth spring-driven motion [Phys. Rev. E. 97, 053301 (2018)] to simulate ring-down measurements in two setups where domain wall dynamics is induced by mechanical motion. These include a single thin film with a domain wall in an external field and a setup mimicking a magnetic cantilever tip and substrate, in which the two magnets interact through dipolar interactions. We investigate how various micromagnetic parameters influence the domain wall dynamics actuated by the oscillatory spring-driven mechanical motion and the resulting damping coefficient. Our simulations show that the magnitude of magnetic friction can be comparable to other forms of non-contact friction. For oscillation frequencies lower than those inducing excitations of the internal structure of the domain walls, the damping coefficient is found to be independent of frequency. Hence, our results obtained in the frequency range from 8 to 112 MHz are expected to be relevant also for typical experimental setups operating in the 100 kHz range.