Magnetic force microscopy study of Zr₂Co₁₁-based nanocrystalline materials: Effect of MO addition

The addition of Molybdenum was used to modify the nanostructure and enhance coercivity of rare-earth-free Zr₂Co₁₁-based nanocrystalline permanent magnets. The effect of Mo addition on magnetic domain structures of melt spun nanocrystalline Zr₁₆Co_84-xMo_x (x = 0, 0.5, 1, 1.5, and 2.0) ribbons has been investigated. It was found that magnetic properties and local domain structures are strongly influenced by Mo doping. The coercivity of the samples increases with the increase in Mo content (x ≤ 1.5). The maximum energy product (B H) max increases with increasing x from 0.5 MGOe for x = 0 to a maximum value of 4.2 MGOe for x = 1.5. The smallest domain size with a relatively short magnetic correlation length of 128 nm and largest root-mean-square phase shift Φ rms value of 0.66° are observed for the x = 1.5. The optimal Mo addition promotes magnetic domain structure refinement and thus leads to a significant increase in coercivity and energy product in this sample.