  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.
