Dynamical Properties of Magnetic Barkhausen Noise in a Soft Microalloyed Steel

This paper investigates dynamical behavior of magnetic Barkhausen noise (BN). The measurements were performed for a soft mild steel at controllable magnetizing conditions: 1) the fixed sinusoidal/triangular waveforms of the magnetic induction or 2) the surface magnetic field. Two vertically mounted Hall sensors were used for direct determination of the sample magnetic field. The BN was detected locally by a surface-mounted coil. A typical two-peak shape of the BN envelope was found to reduce to a usual single-peak profile at the constant field rate. These two peaks were shown to correspond to the regions of the magnetic domain reconfiguration preceding and following the rapid magnetization reversal at the coercive field. In ac magnetizing frequency range of 0.2-30 Hz, the BN parameters followed a nearly square root dependence on the frequency. A low-frequency component of the BN signal, approximately up to 25 kHz, was revealed to contain an important part of the micromagnetic information.