Intrinsic rotational susceptibility measurement in polycrystalline soft ferrites

Abstract
In order to measure the only rotational susceptibility in bulk soft magnetic materials, we have developed a technical procedure by using an alternating electromagnet which magnetizes ring shaped samples in their hard direction of magnetization. So the domain walls motions are reduced and the rotational behavior is approached. We study the influence of the shape of the sample on the residual wall susceptibility value by comparison with previous Globus'study. It has led us to add a continuous bias field in order to strongly tight the domain walls. So the state of the magnetization for which the spins rotation begins is reached with a fairly good accuracy. This experiment gives us the intrinsic rotational susceptibility of the sample. It depends on both the composition and the dispersion state in the magnetic matter. By using a theoretical model, we calculate the value of the intrinsic rotational susceptibility for an ideal 90° rotation of the spins. Results are in good agreement with those of literature.