Nd-Fe-Al, A Spin Glass Transition in a Collection of Superparamagnetic Clusters

摘要

In the Nd-Fe-A1 system, compositions in the range of Nd(sub 60)Fe(sub 30)Al(sub 10) have been reported to be ferromagnetic bulk metallic glasses with high coercivities. Careful examination of both the microstructure and magnetic properties of these materials shows this to be true only in the most general sense. The materials are shown to be nanocomposites, in the strictest sense, with characteristic structural length scales on the order of 1.2 nm. Magnetically, the materials are also composites exhibiting a number of magnetic transitions as a function of temperature. The temperature dependence of the magnetic properties will be discussed in terms of strongly-interacting superparamagnetic clusters residing in a paramagnetic matrix.