Applicability of local magnetic measurements

This work studies the conditions of controllable sample magnetization for local hysteresis and Barkhausen noise measurements. These non-destructive techniques usually utilize the sensor, based on a U-shaped single yoke magnet. Its magnetization potential, however, is too dependent on the measurement conditions. To investigate this problem, we performed the measurements on magnetically different samples with varied dimensions. The magnetization was controlled by a vertical array of two Hall elements measuring the tangential surface fields. The sample field was evaluated by a linear extrapolation of the surface field profile to the sample face. It was showed that the big-sized samples are magnetized in a strongly heterogeneous way. Therefore, it was recommended to use the single yoke, equipped with the local field and sensing elements. The magnetization conditions were suggested to stabilize by means of a feedback loop controlling the local magnetic field/flux waveform, measured by these integrated sensors.