A system for controllable magnetic measurements of hysteresis and Barkhausen noise

Abstract

A specially developed setup for precise measurement of the magnetic hysteresis and Barkhausen noise is presented in this work. A novelty of the setup consists in a unique combi nation of two main features: an accurate local determination of the magnetic field and an improved feedback control of the magnetization process. Firstly, the magnetic field is measured by two Hall sensors at different distances above the sample. Linear extrapolation of this measured profile of the tangential fields to the sample surface gives the true local values of the magnetic field. Secondly, a digital feedback loop for precise control of the ac magnetization process is proposed. The system combines two known methods of magnetizing signal adjustment: linear corrections of the magnetizing voltage amplitude and phase. The presented system is able to adjust the waveform of the magnetic induction or field to the prescribed sinusoidal or triangular shape.This provides stable and physically accurate results, which are independent of a specific experimental configuration.Index Terms-Magnetic hysteresis, Barkhausen effect, mag netic field measurement, feedback circuits.