New design of small-angle magnetization rotation device: Evaluation of saturation magnetostriction in wide thin ribbons

We present here a newly designed device allowing lambda(S) measurements on ferromagnetic ribbons (width up to 30 mm, thickness approximate to 20 mu m). It is based on the ''small-angle magnetization rotation'' method. Estimation of the ac drive field and its homogeneity into the material have been looked into. Calculations by finite elements method (MAXWELL 2D) are compared to H-coil measurements. Influence of de bias field on transverse demagnetizing field has been taken into account. The aim of this work is to analyze, by lambda(S) measurements, the evolution of composite structure (amorphous+crystalline) in accordance with annealing treatments between 450 and 600 degrees C of nanocrystalline Finemet Fe73.5Si15.5B7CU1Nb3 ribbons. Results show that the value and the sign of the saturation magnetostriction lambda(S) are important because they are related to the magnetoelastic properties. Furthermore, the observed magnetoelastic behavior (via variation of magnetization energy in accordance with external applied stress) is highly dependent of the sign of lambda(S) even with a small value (approximate to 10(-7)). (C) 1997 American Institute of Physics.