Magnetic and magnetoimpedance properties of Mn-doped FINEMET

In this study, the effect of substituting Mn for Fe on the magnetic and magnetoimpedance (MI) properties of amorphous and nanocrystalline Fe73.5−xMnxCu1Nb3Si13.5B9 (x = 1, 3, 5, 7) alloys has been investigated. A higher Mn content causes a decrease in the saturation magnetization and Curie temperature. For as-received Fe73.5−xMnxCu1Nb3Si13.5B9 (x = 0, 1, 3, 5, 7) ribbons, the measured values of the MI are 11%, 12%, 16%, 12% and 15% for x = 0, 1, 3, 5, 7, respectively. The magnitude of the MI ratio increases in annealed samples, indicating that they are magnetically softened by nanocrystallisation. The change in MI is found to be ∼70% for the x = 3 sample annealed at 550 °C. It is also found that replacing a small amount of Fe by Mn improves the magnetic softness of Fe73.5−xMnxCu1Nb3Si13.5B9 alloys.