Approach to saturation of polycrystalline materials at intermediate fields: The role of internal demagnetizing fields

• Published in: Journal of magnetism and magnetic materials 1984-01, Vol.41 (1), p.299-302
• Main Authors: Allia, P., Milone, A.Ferro, Soardo, G.P.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Domain effects, magnetization curves, and hysteresis; Exact sciences and technology; Magnetic properties and materials; Materials science; Metals, semimetals and alloys; Other topics in magnetic properties and materials; Physics; Specific materials
• ISSN: 0304-8853
• DOI: 10.1016/0304-8853(84)90202-6

The approach to saturation of polycrystalline ferromagnets at intermediate fields, that is for induction values 0.7-0.9 of the saturation value, is studied, considering the effect of internal demagnetizing fields between grains. In this induction region, these fields give rise to a reduction of the induction with respect to the case of non interacting crystals. A theoretical model is discussed and extended to the case of uniaxial anisotropy materials (Co). Comparison is made between the theoretical and experimental curves of induction vs. field for isotropic 3% SiFe and for Co, and confirms the validity of the model. The cross-over field (that is the field below which the experimental I vs. H curve is lower than the one predicted in the absence of grain interactions) is also found to be in very good agreement with the values obtained theoretically on Fe, Ni, Co and 3% SiFe taking account of the internal demagnetizing fields.