Magnetic Microstructures of Pr_yFe_90-yB₁₀(y = 8-11.76) Nanocrystalline Ribbons by Using Magnetic Force Microscopy

Magnetic microstructure of melt-spun Pr_yFe_90-yB₁₀ (y = 8, 8.5, 9, 9.5, 10 and 11.76) nanocrystalline ribbons in an as-grown state has been studied by using a magnetic force microscope. The magnetic domains are characterized by dark areas adjacent with bright areas in a sub-micron scale and in random distribution. By comparing with the size of the micro-crystals measured from the TEM image, the exchange coupling effect was confirmed to exist in all the ribbons. By using the roughness analysis, the variation of the root mean square values of the phase shifts obtained from the magnetic force images versus the content y of Pr were measured, which is well consistent with the curve of the residual induction B_r versus the content y.