Marcel Brouha

Domain patterns and high‐frequency magnetic properties of amorphous metal ribbons

Domain patterns and hysteresis curves were studied on field annealed amorphous ribbons of Co70.3Fe4.7Si15B10. The domain structure was observed with the longitudinal Kerr effect. Hysteresis curves and permeabilities were measured at frequencies up to 10 MHz and in fields up to 2 kA/m in the length direction of the ribbon. The frequency dependence of the permeability and the hysteresis curves in the MHz range, measured after annealing in a field perpendicular to the ribbon axis in the plane of the ribbon, can be fully explained by assuming that only rotation contributes to the magnetization and that losses are due to eddy currents. Specimens annealed in a field perpendicular to the ribbon plane behave similarly. After annealing in a field parallel to the ribbon axis, however, only wall displacements occur, leading in the MHz range to a low permeability and large additional contributions to the losses.

High frequency magnetic properties of sputtered thin films

Abstract The effects of substrate roughness and zero, longitudinal and transverse field annealing on the high frequency permeability and static hysteresis loops of Co 71 Mn 7 B 14 Si 8 were investigated.

SURFACE QUALITY AND THICKNESS EFFECTS OF AMORPHOUS RIBBONS FOR RECORDING HEAD APPLICATIONS

Smooth ribbons of Co 70 Fe 5 Si 15 B 10 could be obtained by optimizing the relevant parameters of the melt spinning process. The surface structure of the wheel appeared to be the most important parameter. The wheel material, steel or copper, had the greatest influence on the soft magnetic properties of the ribbons in the as-quenched condition. This is due to a different thermal history of the ribbon made on steel or copper wheels. On steel wheels the magnetization process of ribbons in the as quenched condition is governed mainly by wall displacements resulting in a low high-frequency permeability. After annealing the magnetic properties of ribbons cast on copper or steel wheels are almost alike if they have equal thickness and smoothness.