SURFACE MAGNETIC FIELD MEASUREMENT WITH MAGNETIC SHIELDING
In this work we would like to investigate the surface field gradient above an open sample and it is suppression by the magnetic shielding in two magnetizing systems: (i) sample magnetized by an external field of an air solenoid and (ii) sample magnetized by a single yoke. It is shown that the field gradient in the solenoid and the yoke-sample system with large air gaps is very similar. In both cases the magnetic shielding reduced the field gradient by one order of magnitude thus making hysteresis loops measurement much more precise and reliable. Field gradients calculated by finite elements analysis were in agreement with experimental results.
Keywords: magnetic hysteresis, magnetic field measurement, magnetic shielding, extrapolation