Theory of magnetoelastic dissipation due to domain wall width oscillation

This article presents a general treatment of magnetic dissipation due to domain wall width oscillation via magnetostriction in magnetic samples. The domain wall width is modeled as a harmonic oscillator. The parameters governing this oscillator (effective mass, stiffness, damping coefficient and driving force) are derived and expressed in terms of intrinsic magnetic parameters of magnetic materials. The magnetostriction induced damping of wall width oscillations is frictional in nature. An external ac magnetic field serves as a driving force of the oscillator. It is found that the response to the driving force depends very much on the micromagnetic structures of the magnetic domain wall. Different micromagnetic structures lead to different magnetic dissipation for a given external field. Besides giving a quantitative microscopic explanation to magnetic dissipation data measured by magnetic dissipation force microscopy, this theory predicts two new phenomena: on is that there is a minimum driving force for the wall width to oscillate and the other is a new resonance phenomenon, domain wall width resonance. (C) 1998 American Institute of Physics. [S0021-8979(98)08510-7].