Observations on permanent magnets related to damping effects in levitation devices

Microscopic observations applying high, variable magnetic fields on surfaces of high-coercivity magnets reveal hysteretic magnetization changes by domain wall movements. Lines, formerly believed to be grain boundaries, are moving with changing magnetic fields during the magnetization reversal. Domain wall motions are shown on single micrographs which were selected from sequences of micrographs depicting magnetization cycles on commercial-grade magnets of barium ferrite and of samarium cobalt. The observed processes are believed to consume energy; they can be responsible for the damping of oscillations which was experienced before in magnetic bearings.