Magnetic properties and magnetic domain structure of Nd6Dy2Fe82Co4B6 nanocomposite magnets

Nd6Dy2Fe82Co4B6 ribbons, prepared by melt spinning, have been investigated by X-ray diffraction (XRD), thermomagnetic analysis (TMA), vibrating sample magnetometer (VSM) and magnetic force microscopy (MFM). XRD and TMA show t hat the ribbons consist of the alpha -Fe phase and the Nd9Fe14B phase. A hi gh remanence ratio of 0.65 and a relatively high coercivity of 4.9 kOe were achieved in the optimal ribbons. The remanence enhancement is attributed t o the exchange coupling between the magnetically hard and the magnetically soft phases. Comparing the MFM image of the optimal ribbon with that of the exchange-decoupled ribbon, we found that the mean magnetic domain size of the optimal ribbon is larger than that of the exchange-decoupled ribbon, wh ich can be attributed to the stronger exchange interaction between grains i n the optimal ribbons. (C) 2001 Elsevier Science B.V. All rights reserved.