What are reply permeability of the permanent magnet (μrec) and demagnetization curve square degree ( Hk/jHc )?

　　When the permanent magnets are in the dynamic working condition, external reverse magnetic field H or magnet the demagnetizing field Hd shows periodic change, this time as shown in the work point D also shows periodic reciprocating change, defined in the magnet B demagnetization curve of operating point of D reciprocating change trajectories for magnet dynamic recovery line, the line slope is back permeabilityμ rec..

　　Apparently, return permeabilityμ rec. expresses the stability of the permanent magnet in the dynamic condition, it is also the permanent magnet B demagnetization curve square degree, so it is an important indicator of magnetic properties of a permanent magnet. For sintered NdFeB magnet, B demagnetization curve is a straight line, and bHc is approximately equal to Br, the return permeabilityμ rec. is equal to B demagnetization curve slope and μrec.=1.03~1.10. μ rec is small, the magnets in the dynamic working condition stability is better.