in the letz's law video it shows that when
1 you move the magnet closer it rises the voltage (magnetisation happens)
2 ( neutral state happens - a mix of two curves of time of creation of magnetic fields)
3 you move the magnet away it rises the voltage in reverses direction (reverse magnetization state happens)
so every step takes time (start magnetization, magnetization,lenz magnetization reversal ...)
and the result is like sine wave
i guess each material has its own magnetization time curves
so each material has its own optimal oscillation frequency
i guess a magnet could be replaced by a coil and when there is resonance you need very little energy to keep it resonating and the output may be the same.
the video i was watching while i got the idea:
http://www.youtube.com/watch?v=VPxdl1zpcC8&feature=PlayList&p=20F75684405C8A24&index=5
I think this may be what you are headed for:
http://cm.physics.tamu.edu/seminars/K_Romanov_09_19_07.pdf
BTW: It is Bloch NOT Blotch (for other posters I saw, not you)