I wonder what the time scale to demagnetize a fully magnetized permanent magnet with an external magnetic field is. The temperature is assumed to be constant.
I found a reference 1 for specific cases, the time scale for a full magnetization reverse is $10^{-9}$ sec.
But I do not know how to apply the method to real permanent magnets, such as sintered NdFeB magnets.
Say we have the demagnetizing curve (M-H curve) of a permanent magnet, we restrict the problem to the recoil line of the demagnetizing curve, see the figure above. I have the following questions:
- What is the time scale of demagnetizing the magnet from point c to point b?
- Is it possible to add the magnetic viscosity in real magnetic materials, so that the time scale of the demagnetizing process is large (for example, $10^{-2}$ sec)?
Refs.
1 Kikuchi, R. (1956). On the minimum of magnetization reversal time. Journal of Applied Physics, 27(11), 1352-1357.
