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

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.

Bursty magnetic friction between polycrystalline thin films with domain walls

“…At small disorder strengths, there's very little domain wall pinning with all grain sizes, and thus the grain size has a negligible effect on the average energy dissipation, the magnitude of which was roughly P = 10 − 30 pW, which is still quite high compared to purely monocrystalline systems 35 . When the domain walls begin to pin more strongly, the effect of grain size becomes more pronounced.…”

Transition between the stick and slip states in a simplified model of magnetic friction

“…The microscopic friction mechanism is an important subject of condensed matter physics and engineering [1][2][3][4], and various factors in this phenomenon, such as the lattice vibration and motion of electrons, have been studied [5][6][7][8][9]. In particular, magnetic friction, the frictional force generated from the magnetic interaction between spin variables, has been extensively studied in recent years [10][11][12][13]. To understand the mechanism of magnetic friction, many types of theoretical models have been proposed and investigated [14][15][16][17][18][19][20][21][22][23][24][25][26].…”